I always advise friends to buy the biggest unit that they can afford (same for Macs, iPhones and now iPads). In the long run, you end up using as much capacity as you bought. Otherwise, it doesn't matter where you buy your iPad, Apple will service it no matter what.
Hold off on the $69 Apple Care coverage until about month eleven (like, put a reminder in your calendar with alarms). You can add it at any time during the first year. Good insurance against an expensive mobile product...
Piko
The only problem with holding off on purchasing the Apple Care coverage until month eleven, IIRC, is that free phone tech support is only for the first 90 days with the standard warranty. After that, you pay without Apple Care. So you'd have about eight months of dead time. Also, there is the potential for forgetting to purchase Apple Care before the deadline.
And I do whole heartedly recommend Apple Care. It's well worth the cost and is actually a bargain compared to most insurances. Huge piece of mind.
As far as size, I was debating the 32gb wifi. My wife saw the $100 difference and immediately said get the 64gb. If you can afford it, always get the largest memory that you can. It's better to say you have too much memory than not enough.
I waited to get mine thinking it wouldn't be a problem finding them. I was more than a little wrong. Ordered on Saturday night of this past week. Won't ship until July 6th with delivery July 9th. To say the wait is killing me is an understatement.