I use 2 22" monitors, 1 for track view and one for mixer view (one of them is an HDTV), then I have a 19" monitor I keep the browser open on for drum loops and synths.  That works great for the way I do my recording.

I actually just upgraded my monitor setup.  Specifically, I sold a Mackie Control Universal and bought a 27" Acer touchscreen.  I bought a new video card with it, too.  A GEFORCE GT640.  With that, I have a 42" LCD and a smaller 22" or so ViewSonic mounted to a pivoting arm.
 
I also just upgraded to X3, although I haven't installed it yet.  I actually haven't had the chance to use the touchscreen either yet.  It's connected...I just need to go through the install process and what not.
 
I definitely like the looks and the idea of it all!  I'll get to see if it all works out well tomorrow.

For me its more about resolution than size. I have a 24 inch 1920 x 1080 and I can see the point in going any larger at that resolution unless you need to work a long way from the monitor or have poor eyesight.
 
I have considered adding a second 24" 1920 x 1080 but space is an issue for me. At some stage I may go for a 27" 2560 x 1440 but they are expensive at the moment. Someone mentioned a 29" wide screen 2560 x 1080. The issue for me would be the vertical resolution is only 1080. I feel more vertical resolution would be the most helpful thing for me. Another reason whay I may prefer a 2560 x 1440 to dual monitors. 2560 x 1440 gives you 89% of the screen realestate of dual 1920 x 1440

Dude Ivey
I use a 32 inch HD TV. I like it but I wish it was bigger!

The same here. 32 inch HD TV.  The down side is 720p instead 1080p = Screen resolution of 1366x768.  Wife bought it last year for my 29th wedding anniversary.  April will be 30 years...wonder what I can get this year.