I am looking for options for playing live and using projects in Sonar Platinum as accompaniment. I have just begun to research this but I haven't really found anything terribly useful so far. Could anyone help point me in the right direction or at least give me some information on similar solutions that you employ?
 
Forgot to mention that I am using Windows 8.1 on a 64-bit laptop. I run a Line6 UX2 into my desktop with Sonar and I assume I could use the outputs on it though I have not yet tried it. I am interested in other options aside from that device, however, as I am using a Yamaha THR10X for guitar at this point.

If using simple accompaniment (single track), using a laptop might be unnecessary and prone to potential issues (definitely test your setup).

I have actually used a cell phone with a Y-splitter cable for this with RCA->1/4" tips (headphone jack). For single tracks is convenient and small.

I freeze everything I’m not playing live. Than it works most times. But I also have a portable recorder with the playback music as wav. If you don’t have to control or sync external gear via MIDI, and you are not playing virtual instruments live, than there is no good reason to run the DAW. Take a look to recorders like Tascam WR22 or better. They do a very nice job. From my point of view that is a solid solution. Yes, it is playback - but it is the same by pressing Play at the DAW...
Another way is using the Matrix view and a Controller to arrange the songs live.
 

I used to gig with a laptop, and I play keyboards.
 
If you have the means to do it, I would recommend with 8 8 GB of memory, and 2  internal hard drives, for performance.
 
I would also suggest you create exports of all your songs, with the appropriate tracks you are playing live removed, and then use Matrix in Sonar to stage playback of only the simple audio.  There is no need to have to load projects with all the tracks and synths and effects present, since you are only playing back audio to play live with.
 
Bob Bone
 

I've been a solo performer since the 80's starting with 200lbs of midi gear and an Atari computer. 
Read my web pag to see how I'm working now. I recommend mastering your backing tracks to stereo WAVE ( or good MP3). I use a netbook or a laptop because I can control it with a foot pedal. I think there's a foot pedal for ipads now too. 
http://www.cactusmusic.ca/johns_rig.htm