I wanted a small camera to take to Disney on our vacation so I opted for the D3100.
Wow, it's tiny and feels totally foreign in my hands compared to the full body D3S & D3 I'm accustomed to.
I haven't read the manual yet, but I've been playing around with it.
Here's a test using the 70-200 f/2.8.
I'll probably have a 50mm and a 70-300 for the trip unless I have a LOT of sales between now and then. Then I may get the new 28-300.