As others have said, 3G is worth it when you are in a pinch. If you don't mind carrying around an extra box, the mobile hotspot alternative (Verizon MiFi or something like it) is money better spent in my opinion since it's not limited to just the iPad.
One other thing, if you don't mind waiting a few months, you might want to hold out for the iPad 2.
One other thing, if you don't mind waiting a few months, you might want to hold out for the iPad 2.