My "focus" for the next year or two will be to accumulate some nice Canon glass to use with it. First stop will probably be the EF 24-70 2.8 L , or maybe the EF-S 17-55 2.8 , though more likely the former.
Unless you're planning on going FF very soon, from an optical standpoint I'd recommend the 17-55mm over the 24-70mm for the 7D. Personally, I think 24mm on a 1.6xis not wide enough for a 'general purpose zoom' since it starts at 38mm FF equivalent, which isn't even wide angle. On a crop body, the 17-55mm is sharper and has less CA than the 24-70mm (although it does have more barrel distortion at the wide end, and more vignetting wide open). Also, even though the focal length is relatively short, I find IS to be a big help (for static subjects only, obviously). However, if you plan to shoot a lot in the rain the 24-70mm definitely makes sense (as would the 241-105mm f/4L IS, which is what I added to my kit to use on the 7D in the rain, but I still used the 17-55mm much more often, at least until I got a 5DII).
Yes, I am really torn between these two lenses.
One the one hand:
* Yes, I *do* want to own an L-series lens, partly "just because...". Shouldn't matter, but does.
* I would often like to take just that "L" lens out, and so not worry if it rains. Both lens and body have water sealing.
* I tend not to shoot wide-angle (at least at the moment anyway), so I'm less bothered about the 17-24mm range
* I can take the "L" with me if/when I "upgrade" to FF in the (not very near) future
* The "L" will, as you say, likely exhibit less vignetting on a crop camera like the 7D
Yet on the other hand:
* You say the optical quality on the EF-S is higher - That is and should be a big, important factor
* The EF-S has IS and the EF L doesn't (yet).
* The EF-S is cheaper.
Taken together, all of those competing points create quite a dilemma!
Thanks for your thoughts!