Is the 3G option worth it? You could always tether from your phone and give it wifi so you dont really need to get a plan for it unless you want to waste money... but what do you think?
if you do tether, can you use maps properly on a wifi only ipad? will it display your location just like on the iphone or close? it might be even better if it did, since you're also using the phone's gps instead of just cell towers
if you get a 3g ipad and jailbreak it, can you run that mywifi (i think) app from cydia that lets you tether your connection? that would be nice if it worked