Hi Bettsmd and welcome to the forum,
 
I have a friend who wants to buy a DAW and was interested in Sonar after I gave him a demo of Platinum. The question then arose of which version would suit him. So we have spent quite a while examining the specifications of each version on the link that JesseG provided and even more so on the Versions Comparison page. 
 
I know that you aren't a newcomer to DAWs but maybe even the $49 Sonar Home Studio would meet your needs? I would definitely go with Jude77's suggestion of trying a demo version and see if it will suffice. Of course there would always be upgrade paths open to you if you found in time that you needed the functionality offered by the other versions.
 
I have used the Staff View more than I thought I would for entering mainly piano music notation and it is usable once you get used to it and provided you aren't entering massive orchestral scores. Don't expect Sibelius functionality and you will be fine. That said, I do find the Piano Roll View the better way to enter music that I am not actually playing and it is quicker to use than staff view (for me at any rate). 
 
Hope this helps,
ZT

Glad to help, though when I re-read my reply it seemed quasi-illiterate!  I actually am fairly intelligent.
 
And, as others have noted, Jesse G is indeed a good guy who has helped me out more than once.
 
Again, best of luck with your music!

Bettsmd
Not cruel, Jesse, just rude! It would not have taken you any longer to answer my question than to patronize me like that!
I have spent 3 hours on the website and combing the internet for information and have yet to get an answer.
Hope you enjoy your high horse!

Jess is a good guy. Think about it...you are on the cakewalk site.
3 hours is a long time to be bumping in to walls and not find yourself any information.
 
He was only stating the obvious and in my travels I have found when asking for help, its never a good idea to bite the hand that is trying to help you.
 
You say you need to be able to write out the music, is that staff view, or can you use Piano Roll View ?
Because in my opinion, staff view does what it should but isn't winning any awards anytime soon.
However, if you understand the way a PRV works, you can write out almost anything in detail there.

If you need more of a notation program than Sonar is providing you might want to look at the free  Musescore2: https://musescore.org/
 
You can write your score here, save as a MIDI file then bring it into Sonar.

I agree with the suggestion to download the trial version; that's how I started way back in the '90s. I tried Sonar, Cubase, etc., and settled on Sonar. Then I upgraded to Home Studio, and took advantage of upgrade specials as they became available.
 
As far as whether or not you can use it for writing music, "writing" is kind of an ambiguous term. As mentioned above, the staff view is functional, but the piano roll view (PRV) is better. If you have a basic MIDI keyboard, you can use that to record tracks with the included instruments (VSTis), and there are plenty of free VSTis available on the web that would be enough to get you going. (Computer Music magazine, published in the UK, also includes a ton a free effects and instruments with each issue.) 
 
Hope that helps!

Just to pile on a bit...     Something like Sibelius would certainly exceed what SONAR can do from a pure Staff View perspective.   However, WRK files can only be opened in Cakewalk applications, so there's a trade-off.   I do agree with Chuck though - if you can use the PRV it would provide a great balance to the Staff View, and, would allow you to use your existing WRK files if SONAR's Staff View isn't completely to your liking.   Of course, only you can determine that.