I was recommended to use Ipass - no fixed charge, and you pay per second. Access points all over the globe. There are two price scales, an "800" one, and a "normal dial-up" one.
They ask for $100 upfront, but will refund any balance when/if you cancel. For regular travellers going to all sorts of places, it's ideal.
I'm hoping that my laptop, cellphone, and GPRS will work in CA, NV, AZ and CO. If it doesn't, it'll be back to SMS while I'm there (I know that works!)