Had a lot of time on my hands this weekend so decided to do some testing on my T61 Thinkpad that "was" dual booted to WIN7 and Ubuntu 12.04. So on the Ubuntu partition I tested several different versions of 13.04, xubuntu, ubuntu/Unity, and ubuntu/gnome. I did not include lubuntu in this mix. I tested it extensively at 12.04 and found that it was just to hard to customize to my liking.

Overall, each installed quite nicely and operated almost bug free. Here are my quick observations.

ubuntu/Unity:
I like the interface and would prefer to use it. However, the HUD just is a pain and the one reason why I can't.
Yes, it uses the most resources.

xubuntu:
I have always liked this distro, it's like an old friend, comfortable and known and the polish has improved significantly over the past few releases.
I do wish they would ditch the out of the box splash screen at login time for something a bit more attractive.

ubuntu/gnome:
I was hoping to see 3.8 but that was not the case. However, with a few gnome extensions it is very nice. One (dash to dock) keeps the dash visible all the time like Unity so its a very comparable product.
Seems to use less resources than Unity.

In the end, I am going to keep ubuntu gnome since for me, it's just little bit better than the other two. But, I still like xubuntu