Hey Sean, welcome to the forum, nice shots.
I dont have any of the Canon wide angles, as I usually cant afford them. But I have a few Sigmas and I'm very happy with them. I have both the 17-35 f/2.8-4 and the 24-70 f/2.8. They both are great lenses, very fast and half the price of the 10-22 Canon.
I used to have the Tamron 28-210 f/3.5-5.6 but didnt like it too much because of the slow focus and the fact that it had a 6 foot minimum focusing distnace
I sold it as a package with a Digital Rebel so I could move up to the 30D and the wider faster Sigma.
You also might want to checkout a few of the lenes that offer both wide and tele-photo as they make for great walk around lenses. We have a Canon 28-105 that is very small and great for when you dont want to draw any attention to your camera. Say in a museum, or in a busy public setting. Put one of those big lenses on and it's impossible to walk around without everyone commenting on the size of your outfit.