If you already have an XSi body and like it, the 60D may be a better fit for you. I think it's a wee bit bigger than the Rebel bodies, but still smaller than the 7D body, which is practically a full-sized body (minus integrated grip of course).
Also, for the subjects you mention, there's no reason (really) to use a 7D.
You might also consider just keeping your body and upgrading your glass. I took a look at your flickr and noticed you using (I'm assuming) the 70-200 for the prom shots indoors.
Nice shots, but perhaps sell the 70-200 f/4 for a f/2.8 version? (there's definitely a weight increase, though).
You could also upgrade your kit 18-55 to maybe a Canon 17-55 IS 2.8 or Tamron 2.8 if you wanted to, etc. etc.
Basically - what about your current body do you not like?