Hi tracy, it completly depends on where and how you want to use it. I have a WIFI only iPad 1 , and I have never found the lack of 3G a problem , as I work in large cities, and am never far from free wifi if I need it.
If you are going to be away from WIFI often, but still need connection to the web then 3G is definitely required.
I use mine for mainly reading books and periodicals when on the move. Once I get to work, then I can use it for email and the rest. Most of the apps allow you to download content , which you can use with a connection.
You also might want to look at the new Google Nexus 7 tablet, as they are full functional 7" models, WIFI only but very inexpensive, @ £159 for an 8GB version.
Google Nexus 7