Make sure you get a roaming data plan or you'll bankrupt yourself using data while in the U.S.
I'm with Robbers, er.... Rogers. They charge $6/MB if you don't have a plan. If you go to the States often, for a $10/month charge, you can use your regular data plan in either Canada or the States with your same data limits. If you travel there less frequently, you can put a US Data add-on on your iPhone for while you're there. There are a number of different options, you'll need to figure out what's best for your expected usage.
Although even with a package it's highway robbery, it's still cheaper that using the resort 'wired' internet access and you can use it wherever you go. I take a laptop to use in the room and tether it to my iPhone.