Personally I wouldn't bother with the beer in the waterpan, you get a nice smell while cooking but I don't think it improves the meat flavour. You'd be better just drinking the beer
If you can get any of the following while you're over in the US you won't be disappointed:
1. Blues Hog Original Sauce
2. Blues Hog Tennessee Red Sauce
4. Cow Town - The Squeal Rub
5. Cow Town - Sweet Spot Rub
6. Plowboys Yardbird Rub
7. Plowboys Bovine Bold Rub
8. Obie Cues Brisket Rub
These are more specialist products so it'll depend where you are staying as to whether you can get them.
Stuff you'll be able to get from Walmart that's definitely worth a punt:
1. KC Masterpiece Original Sauce
2. KC Masterpiece Honey Sauce
3. Sweet Baby Ray's BBQ Sauce
4. Famous Dave's Sauce (a number of varieties)
5. KC Masterpiece All purpose Rub
6. Lawry's Seasoned Salt (a great one to have in the cupboard)
Apologies if you're already familiar with rubs and sauces, just thought I'd share the ones that I've found to be good.