Ok, I'll answer here rather than there...
24mm on a 7D is not wide angle - it's really just touching into the normal range. If you don't have anything wider than 24mm, you will quite likely be missing out on opportunities, unless you're willing to forego wide angle shots.
So, if you want wide angle on the 7D, you're looking at the EF-S 17-55mm f/2.8 IS, the EF 16-35mm f/2.8L II, or the EF 17-40mm f/4L. The last two are weather-sealed and FF-compatible. The former has IS and will deliver better image quality on your 7D. Down into the ultrawide end, your only Canon choice is the EF-S 10-22mm. If your budget permits, the 10-22mm plus the 24-105mm would be a good combination, but not fast. Overall, though, I think your best bet is the 17-55mm. You can always resell it later if you get a FF body - it will hold its value pretty well (quality lenses do). Also,I think the 5D line isn't really a replacement for the 7D if you shoot wildlife/sports, more of a supplement, which is why I still have the 17-55mm to use on my 7D, even though I now also have a 5DII.
Have a great trip!
Ps. RE:
Originally Posted by dsm363
That rumor was nearly a 'sure thing' in 2009. No lens yet. Don't hold out, IMO. Get the 17-55mm. Just my 2¢. []
Reply With Quote