A note on bear canisters... They are great where required, but pretty heavy (my Garcia weighs 2 pounds 12 ounces). Most places in the US where you will be likely to camp while bike touring will either have bear lockers, or not have bears that are skilled at defeating schemes for properly hanging food.

I have not yet done the Southern Tier (I plan to early 2012), but on the Trans America, in the Sierras, on the west coast, and along the Santa Fe trail I never wished I was carrying my bear canister. I prefer to travel light, but for those who don't mind carrying a lot of heavy stuff a bear canister does double as a stool.