I have the Sigma 10 – 22 and I love it. I’m sure you got the best lens for your trip as it’s a super landscape lens. Hope you enjoy your trip, I’m sure you will and shoot loads and post them here for us all to look at and get jealous.
I also have the Canon EF-S 10-22mm. I think it’s a great lens, however I don’t use it so much as I don’t often wish to shot in its focal length range.
If you are using it for landscapes think about getting a graduated ND filter, I missed some good opportunities on a recent trip as I didn’t have one (or a tripod to make multiple exposures).
It’s also great for taking close-up shots of cows and other animals.