Hi,
I wish I had the broadband to leave at home,..
I don't, so Earthlink has been my choice for years. They do limit the number of connections to one instance per account. They used to allow multiple connections but they charged by the minute for the second connection. Now, you just get an error when you try to connect twice.
If you can work out the sharing details, I would suggest giving the chosen ISP a valid card to charge every month so that you don't have to rely on one person paying the bill. Check out NetZero for cheap access and national phone numbers.
But, before doing any of this, check to make sure that your broadband provider doesn't supply a dial-up account for "emergencies" or travel. Many do and most don't charge extra for it.
When I can, I purposely chose the hotel with ethernet/wireless access. It's amazing how many are providing that now and many are not the premier hotels so per room costs are still reasonable. Some provide the access at no extra charge. Since there are usually two of us traveling together, we carry a small ethernet hub and share access in the room so even if we dial-up, we limit the phone calls...helps where the hotel charges for even local calls.
(wishing I could figure out why our two laptops with wireless can't bridge to share the internet connection although file sharing works great..hhmm..another topic)
Here are some wireless links that may interest
Hotspot ListWiFinder