Hi,
  I have been using Sonar Platinum with a basic beginner setup with focusrite 2i2 audio interface and  BCF2000 for DAW control. I have "some" budget and want to spend on the right gear with the intention of getting "better sound" and improving productivity. I want to be able to record  instruments (mostly solos) , be able to switch between a pair of monitors to A-B my mixes, and get a better DAW controller for Sonar (since the BCF2000 has worn out and some buttons are not working any more). To be able to do all this, to the best of my knowledge, I think I need the following (please validate)
 
1. An 8 channel mixer
2. A monitor management hardware like the Presonus Monitor Station
3. A control surface substituting the BCF2000
 
Questions that I have :
1. Is there any one piece of hardware that will help with points 1,2 and 3 above or a combination of any 2 of the above? To my knowledge mixers cannot be used as midi controllers. Is there any brand that does both in one ?
2. What are the best options for a control surface for Sonar ? Something that can control not just navigation, volume, mute, solo,panning but also provide VST control and particularly pro channel control . I dont want to spend more than 500$ on this given that this is not going to improve the sound quality in any way.
3. For monitor management, is there anything better than Presonus Monitor Station in the less than 500$ range ?
4. Is it worth spending on an expensive interface like RME. Besides additional I/O ports, will it bring a significant difference in the sound quality compared to Focusrite?
 

There are less-expensive options, but this is pretty much an industry standard for monitor switching.
 

I'd question the need for an 8-channel mixer. Yes, it could definitely come in handy for recording a whole band, a multi-mic drum kit, or hooking up many outboard synths. But if you're just recording guitar, a mixer may end up mainly taking up space. Multi-channel audio interfaces such as the RME you're considering are also mixers. I put my console in the closet 12 years ago, finally gave it away 6 years ago, and never missed it.
 

Ok...I thought so. The mixer  is probably an overkill for the kind of work I do.

My Quad Capture only has one pair of TRS outputs so I picked up this box from Hosa.  I don't have a second pair of monitors though, so I'm really using it as a monitor on/off switch.  I got tired of reaching behind the KRK's to power them on/off.
http://www.sweetwater.com/store/detail/SLW333
 
I do have a couple pairs of headphones.  I use this splitter to avoid plugging/unplugging at the QC's single headphone jack.
http://www.sweetwater.com/store/detail/JIBS

what kind of music?
You don’t mention what speakers you have?
Room treatment?
Mics?
What does “mostly solos” mean?
What does “some budget” mean? 
What does “better sound” mean ? 
 
The Xtouch behringer controller seems like a better controller than the BCF2000.
 
If you want a mixer/control surface, I just noticed some of the Allen and Heath mixers seem to have some daw controller aspects built in as they are also interfaces. I believe Presonus mixers have some  Daw integration also.
 
I would think an RME interface would outshine the Focusrite. Probably not by much though. However, If you are recording a lot of cumulative tracks, the ’not by much, could add up to ‘quite a bit’.
 
I don’t think any of the products you mentioned will give you ‘better sound’ except maybe the RME.
Probably the best way to get better sound would be to have better room treatment. 

timidi
what kind of music?
You don’t mention what speakers you have?
Room treatment?
Mics?
What does “mostly solos” mean?
What does “some budget” mean? 
What does “better sound” mean ? 
 
The Xtouch behringer controller seems like a better controller than the BCF2000.
 
If you want a mixer/control surface, I just noticed some of the Allen and Heath mixers seem to have some daw controller aspects built in as they are also interfaces. I believe Presonus mixers have some  Daw integration also.
 
I would think an RME interface would outshine the Focusrite. Probably not by much though. However, If you are recording a lot of cumulative tracks, the ’not by much, could add up to ‘quite a bit’.
 
I don’t think any of the products you mentioned will give you ‘better sound’ except maybe the RME.
Probably the best way to get better sound would be to have better room treatment. 

I am not looking for mics and monitors or room treatment. I have those covered. To keep the question short, I just mentioned what I am interested in. XTouch seems like a popular option. Does it control pro channel as well ? I understand its only the audio interface in the above like that makes a difference to audio quality.