I just recently contemplated the same question, moving from a T1i to something a bit better.

While the T1i has served me well I had some of the very same concerns that you have mentioned, particularly the sealing since most of my shooting is done outdoors. I ended up with a 60d (just this weekend), 24-105 combo that I am so far loving. In addition to the sealing, the ergonomics, top lcd, and decreased shutter delay/increased fps are providing a much different experience than my Rebel. I haven't really had much of a chance to note the differences in focusing and metering as of yet but from what I have read I should see an improvement. So far zero regrets on the purchase.

I had considered the 7d but at the end of the day the 60d accomplished most of what I was looking for. I wasn't ready to step into 5d territory, but I'm sure the mkIII, 24-70 setup would be an amazing alternative.