If I were outfitting my studio from scratch I'd go with:
 
Sonar Platinum
Wait a few months and get a new MacBook Pro to run the Mac version of Sonar. Platinum has everything you'd ever need in a complete software studio. It's well worth the modest up-charge relative to the other Sonar versions. ...and I think it's gonna be killer on the new MBP.
 
Native Instruments Komplete
Arturia V Collection
Native Instruments Kontrol 49 midi-keyboard
Kontrol is built to work with Komplete and The stuff in the V-Collection right out of the box. You can have all three of these for much less than a workstation keyboard. Your really don't need the workstation keyboard if your going to be using it in front of Sonar all the time. If you are going to play live or don't want to work within a DAW, workstations are great.
 
Focusrite Scarlett Interface
I have the 18i20 and its the best interface I've ever used. The second generation of the series that Focusrite just announced makes me want to get another one (6i6) for my mobile rig.
 
Keith McMillen QuNexus
Amazing device for travel. Works perfectly with both my MBP and my iPads.
 
The only other DAW I would seriously consider is Logic. I think Sonar has a far superior workflow, but the Logic Remote app on the iPad is friggin' unbelievable.  ...and Logic is the only way you are going to get your hands on what is left of Camel Audio's Alchemy.

Not to mention Logic is up to version 10.x on Mac and actually owned by Apple. I love Sonar but I would never recommend a beginner get an Alpha version of any software as his main investment.

Sanderxpander
I love Sonar but I would never recommend a beginner get an Alpha version of any software as his main investment.

I agree with this

 

tlw
Doing basic things - recording, MIDI handling, adding effects/plugins, everyday audio editing - is the same in all versions of Sonar. 
...
So Platinum is no harder to learn than the other versions of Sonar from the point of view of getting the basics done. What Platinum does offer is far more plugins, so, for example you don't just get a compressor but several quite different compressors etc. 
...
As for keyboards, I'd suggest considering a MIDI controller rather than a workstation. A DAW is a far superior workstation in many, many ways to a keyboard one. 

A lot of key points and great advice in this post.
 
If you can afford it (and sounds like you do) definitely go with Platinum simply because of the great extra virtual instruments you have with it, e.g. Z3ta (albeit Classic), Dimension Pro, TruePianos... See here for the comparison: http://www.cakewalk.com/Products/SONAR/Versions#start .
 
As stated, a Workstation is really a waste of money IMHO. A Workstation allows you to do sequencing, recording, composing, etc... which is exactly the point of using a DAW, except it's much more limited than a DAW. It's like looking for a car for your new shiny fancy caravan and deciding on buying an RV :D. Just go for a MIDI/controller keyboard (i.e. without its own sounds) and ideally one with extra controls like transport (Start, Stop, Record...), faders and maybe even drum pads, e.g. the Akai MPK series. The only disadvantage to that is that you always have to turn up your PC and DAW to play. If you would also like to just be able to push a power button and start playing, you will need a synth/keyboard, which also has the benefit of extra sounds in addition to the VSTs. Also as far as learning is concerned, this has the advantage that you will also learn how to record audio and better be aware of the differences between audio and MIDI (a common confuser for beginners).
 
Also don't forget budget for good (powered) speakers and/or headphones.

I would say buy it. If you get a simple, stripped down version of Reaper or StudioOne or whatever, you could find yourself running into limitations. Yes, simpler DAW's can be less of a learning curve to some extent but with the simplicity comes limitations. I tried the others along with Acid and found myself getting frustrated.
 
I will echo what Mr. Anderton said, you can use as little as you feel comfortable with but still have the option for more advanced features as you grow into it.
 
As a hobbyist and long time CW user, I found Pro was a good (re)entry. However, I'm also looking to upgrade for the additional instruments - not that I need them but I want them. I just have to justify the additional cost strictly for an occasional hobby.

As a 'retiree with a computer and musical background' who uses SPLAT almost exclusively with midi I would say "go for it". I've been using Cakewalk for years and have found it to be reliable and user friendly. I've only scratched the surface of what it can do but always find it interesting getting just another bit further under the hood.
The other great advantage is this forum - I don't post much but visit often to see what's going on and to pick up tips and hints both from a Cakewalk software perspective and from the wider computer issues view.
Good luck with whatever you decide!

husker
As a little background, I am about to "retire" from the majority of my volunteer work, and am looking for a hobby to take up the time.  I am an IT guy who is obsessed with music, and grew up playing the piano.  What better hobby than to marry my two interests (IT and music) together?   I'm a much better IT guy than I will ever be a musician, but I look forward to learning and tinkering over several years. Half the fun for me is learning how things work and generally "messing around."  
 
My plan is to buy a keyboard workstation (probably a Yamaha Mox8 or Roland FA-08), a NI Komplete Audio 6 interface, and a DAW.   I play no other instruments, and cannot sing; so, for me, I will be limited to the keyboard and DAW.

Since I have almost the same background (well, I think I can sing, but everyone else, including my family, has different opinion), let me make several comments.
 
* If you have real acoustic piano and want record it, you probably want to use full version of Melodyne for correction. Once you register the version which comes with Sonar, you get time limited offer to upgrade. Not cheap but worse it, and it will be hard to get the same price once the offer expire.
* if you do not have real piano, think about Digital Piano. Some of them have workstation like capabilities. But the point is the keyboard. There are DPs with good piano like feeling (Kawai VPC-1, CS), other with "acceptable". Try to find a store where you can test many. Note that Sonar has no good Piano VST.
* Platinum is great for testing/learning audio effects and the difference between them (significantly more then lower versions), has several extra instruments in limited edition, 3packs of AD2 (full version of good drum instrument) and a set of sound samples to make fun with. Lifetime updates. I have joined the train back in X3 time and while I have probably not used big part of that huge package, I have never thought that saving some money with simpler version could be a better option for me.
* if you do not plan to record analog sound with processing (guitar, mic), the sound interface is not so important. All interfaces with own ASIO drivers have reasonable for MIDI latency. But do not forget about Monitors and Headphones. You will be unable to understand what all these EQ and Compressors are doing throw PC/Workstations speakers nor throw a phone headset. Several instruments mixed together will sound "wrong", but the problem is to understand how to fix that.
 
 

Maybe you've already done this.... but why don't you download and try out Sonar, REAPER, Studio One, and Cubase (cubase elements can be demo-ed w/o a dongle and you really should at least see how Steinberg does it)?
 
All have a lot of bang for the buck and can make music.   It should be less cost based (unless you're really strapped) and more of how you like to work and what flow for you.  DAWS are definitely one type of program that depends on HUE and how much you enjoy the UI experience.   And it's different for different uses:  someone using it for recording bands, vs someone using it to write / record vs orchestration vs ??? will all give you different opinions on the same software.

Though this is a little dated (It is for Sonar X3), this video for $9.99 covers a LOT of MIDI with SONAR.  The techniques remain the same with the current version of SONAR.  I also am an IT guy that has a passion for music.  I cannot play keyboard, so I just got a MIDI guitar!  At any rate the below video has at least got me making sounds with it in SONAR:
https://shop.cakewalk.com/1244/catalog/product.151198/language.en/currency.USD/?id=KytbcDlxWS

There is also this one at Groove 3 for $20.00 and it is up to date and basically covers SONAR Platinum:
https://www.groove3.com/cakewalk-training-video-tutorials/SONAR-Explained
 
Then when you get through this, there is an Advanced Version:
https://www.groove3.com/cakewalk-training-video-tutorials/SONAR-Platinum-Advanced
 
You tube is a free way to view MANY Sonar videos as well.
 
Good luck and welcome.  BTW, even if you choose not to use SOMAR, please come back and let us know what you did choose and why.  It may help someone in the future!
 
(I do not work for Gibson, Cakewalk or any other entity that would profit off his choice of DAW.)