Thanks Mav!
Would you think having 17 - 50 would be better for shooting portraits?
There's a compromise here. 28-70 is definitely better for portraits since 70mm will give you a bit more distance from your subject than 50mm. But if you want to take a group shot and don't have a whole lot of space, suddenly 28mm is not gonna be wide enough. This is where a 2nd body comes in handy. :mrgreen:
I could do a 17-55 f/2.8 type lens on one body to cover group shots and the mid-range, and then an 85mm f/1.8 prime on the other for portraits. Or reverse it and use a 28-70 f/2.8 on one, and the whatever you have that'll go wider (even an 18-55 kit lens) on the other for group shots. You don't need a wide lens that also does f/2.8, because usually you want to be stopped down for those to make sure you have everybody in focus. The shorter depth of field from a larger aperture lens can sometimes throw people out of focus in group shots who are at the edge, or maybe a row or two back, depending on how big the group is. Here you just need good lighting more than anything.
Fisheye lenses can be extremely useful for group shots in tight spaces, too. This one I corrected with the Image Trends Hemi plug-in in photoshop. It doesn't look like it, but it was standing room only in this hall. Somebody who also had a DSLR wanted me to take a group shot with their own camera, but even 18mm on their kit lens wasn't nearly wide enough without backing up a lot which was really difficult.
Personally for a budget of $1000 and good event coverage (but on two lenses), I'd go for the EF-S 10-22mm for wide shots or group stuff, and then a 28-70mm f/2.8 type lens for speed and portraits. With one body it's a pain and you have to switch lenses, but you're golden with two bodies.