It is really tough to hit the 5 GB limit unless you do video or high use things like Skype. With 2 people using only Verizon for a solid month (before the iPhone
was jailbroken) we still didn't hit the 5 GB limit. Yes, Verizon has the limit too.
The MiFi/aircard and iPhone
area great combination. You get both networks and 10 GB/month plus have all the iPhone data services which stops you from powering up your laptop
about 50% of the time. I've been answering all of this on my iPhone while resting after arriving in Vero Beach an hour ago.