This graphic guide will tell you what is the perfect iPad 2 for you, depending on where and how you are planning to use it (click on the image to expand).
What experience told us
When it came out last year, nobody knew what iPad to buy. Everyone here got the model they thought could fit them, but we weren't sure. Now, after spending almost one year with it, we know exactly what we - and you - need.
For example, Chris Mascari and Brian Barrett spent extra money on the iPad 3G, but after using it all this time they discovered they rarely used the 3G connectivity. Every time they used their iPads they were in their houses, a coffee shop or a restaurant, where Wi-Fi is almost always available. They are now buying the Wi-Fi model.
I bought the iPad Wi-Fi 64GB. Like Chris and Brian, I rarely find the need to access the internet on the iPad unless I'm sitting down somewhere.
Who really really need 3G connectivity
But none of us here are heavy commuters. My home is close to the office, so I use the NYC subway - where, surprisingly for being the capital of the world, there is no 3G service yet - for only a few stops.
The only people who actually need 3G connectivity are: a) those who commute a lot and don't have a Wi-Fi connection in their trains or buses and b) those who really need to be connected at any time in any place, in the middle of a park, a road or the street. If you belong to any of these two categories, then the 3G is a good option... unless you already have a phone that can be a Wi-Fi hotspot or you have a personal Wi-Fi hotspot. In that case, get the Wi-Fi and use your hotspot for those times when there's no Wi-Fi.
The other deciding factor is the GPS. None of us have used the iPad for true GPS location services. In cities, Wi-Fi geographical positioning works perfectly well. Those who need real GPS in the car or trekking may need an iPad 3G. However, a smartphone will serve that function better than the iPad, since they are smaller, lighter, and their form factor and screen size is good both for cars and walking.
If you are in Europe...
If you live in some countries in Europe - like Spain - you can get a duplicate of your microSIM card and have an iPad 3G at no extra cost, using the same data contract as you telephone. If that were the case here, I may think about getting the 3G just in case. But since that's not an option, I will buy the iPad 2 Wi-Fi with 64GB.