If you're looking at stackable switches, look at the 2920 or the 3800.
If you put in a stack of 3800s you might be able to use that stack as both yuor router and switch, thus saving you space money and power.
Are you looking at 10Gb ports? You get lots of these with the 2920 or 3800-48 ports. (4x 10Gb ports each)
How about 40Gb ports? If so, try the 5900, which is also stackable.