Mark, having used and owned all the cameras you're taking about, my experiences are that when I had the 5DmkII I found that the quality of the 7D was a little better for picture quality, but it failed on the high ISO stuff when compared. So for outdoor shooting/walk around, I tended to use the 7D more unless I wanted really wide shots, then I would pull out the 5DmkII.
If you're shooting everything inside and without flash, the 5DmkII wins for me, but again, if the flashes come out, the 7D becomes a big player because of all the flash control and such.
once I picked up my 7D, my 5DmkII really just became a 2 trick pony. High ISO, and the wide angle full frame ability. I could have lived without it, though I loved it and loved shooting it.
But now that I have the 5DmkIII I wouldn't even think twice about picking up any other camera any time really unless I was trying to get the extra crop from having a crop sensor for shooting wildlife. But even then, the quality on the MKIII is so much better then the old camera, I can crop 100% and not loose much quality at all. I wouldn't do that with my MKII.
I find the colours on the MKIII much more on par with the 7D and MKIII as well where the MKII is lagging behind.
so my advice is maybe to stick with the 7D for a while more before looking and maybe pick up a used MKIII in a year or two once the prices fall. And after you sell your T1i to help bring up the bank to get the better camera
Just my thoughts, don't know if others will agree or not who have shot both.