Here are a couple of videos discussing the issues with wide angel photography (there are many more). As you can see in No.2, there are lots of things you can do in Photoshop in post processing. But as with most things in life, there is no free lunch. You just have to practice.
http://www.youtube.com/watch?v=P2tDU5A36ac
http://www.youtube.com/watch?v=x9uu_K1zDCg

Below you´ll find some photo stitch videos (again, there are lots of them on youtube). There are lots of SW packages, including Canon´s own, for this purpose.
If you get the 24-105L, you will not get the wide angel you are looking for. But, if you stitch multiple images (only 2 or 3 is normally sufficient), you don´t run into the same wide angel distortion problems you´ll get with the 10-22 (at the wide end). And by stitching 2-3 images together, you can get spectacular wide angel images, distortion free, with incredible resolution and detail. It requires some post processing, but that is half the fun. If you go to a place like Machu Pichu and take the time to get this right, you can make very impressive large format prints and have memories for life.

http://www.youtube.com/watch?v=JmSw1p4LSwg
http://www.youtube.com/watch?v=uGf10N5seEM

Have fun
Eldar