Sounds like you have a great adventure ahead!
I haven't tried using their service yet, but Schlotzsky's Deli has free Wi-fi for anybody that wants it. In case you don't know, Schlotzsky's is a "casual-dining" deli based in Austin, TX. We have several restaurants locally and I think they have great food (but I might be biased because I own stock in the company). You can check out their website at
www.cooldeli.com. I did a quick location search on their site and it looks like they have quite a few locations throughout the southern US. If these locations are on your route, it might be a great free access point. I'm not sure that every location will have Wi-fi, but you can get more details on their site. I'm getting my X3i today and will be trying out the service at one of our local Schlotzsky's and will let you know how it works.
Hope you have a wonderful trip!