I have a few Dell 30's myself (run via nVidia Quadro 4500's (now 4600's)).
I like the 2560x1600 resolution, but I dislike the performance hit I take when I run at that res. I run 2 instances of WoW... each on their own 30" from time to time.

The 27" monitors operate at 1920x1200 and offer that comfortable medium between the 30" and the 24".
This gen's LCD's with an HC suffix offer 92% color gamut. The actual brightness of the display is lowered somewhat (most won't notice/50 nits), but the color range is great (deeper colors/vivid colors).
I like the UltraSharp product line due to the adjustable stands and positional/orientation options allowed.

I do wish the 30" offered more than just a DVI input. I can't wait for DisplayPort, tbh.