I've used Verizon EVDO for years. Currently, you want EVDO-A.
It usually works quite well. Not even close to cable modem or FiOS in speed, but about as good as a DSL line, which works okay for just surfing.
You will want unlimited GB. Even with that, there is rumoured to be a limit above which VZ will terminate your account - but it is a lot, more than a normal web surfer will use.
In areas where EVDO is used heavily, you may find slow connections or difficulty connecting. I've experienced this in SF and NYC sometimes, also at techie conferences (e.g. CES) or financial conferences where everyone is on wireless. I'd guess it happens until VZ's local capacity catches up with demand.
I have heard that Sprint has become better than VZ, so say our IT guys. So consider them both. ATT is coming out with a similar service too.
I suggest you use a PC Card modem, rather than a USB modem or a built-in modem. THe former reportedly don't work that well. The latter is hard to upgrade and may lock you into one carrier.
And I agree, make sure you can test it at your apartment and usual workplaces before the return period is up.
I would ask here
http://www.evdoforums.com/ There are all kids of additional antennas and gadgets available. There are even WiFi access points that sit on your desk, you plug the PC card modem into it, and it gives you a WiFi/LAN network in your house from the EVDO connection. This could be handy if you have other devices that want an Internet connection.