Get dual 23" 1920 x 1080 screens as a compromise.
I don't see the point in going higher than a 20" if the resolution is only 1680 x 1024, you just get bigger pixels and no more usable desktop for the extra inches of desk space.
You can pick up a pair of 23" Samsung SM2333SW, 5ms LCDs with DVI and a 1920 x 1080 resolution for just under £300 all in, I think it's the HD resolution as opposed to 1920 x 1200 which is common with computer LCDs that keeps the prices down. Side by side they'd offer a 3840 x 1080 desktop and only use 111cm of physical desk width. They have that smart, piano black finish a lot of LCD TVs do too.
I don't know how they'd be for quality but I've no dead pixels on my SyncMaster 913N in the 3 years I've had it and the colour is very vibrant even with the brightness at just over 50% to compensate for it's very bright back light.