Skyrim is gorgeous. I had a good time wandering around and appreciating the artsy fartsy aspect. But as for really playing it, I did grow a little bored. I can't say if this was because it was genuinely less engaging than previous Elder Scrolls games, or if I just preferred Oblivion. I don't know. But there's definitely tons to explore and tons to do, so you're definitely getting your money out of it (or not, you scumbag pirate). It's cool that you don't select your main stats at any point in the game, so you're free to switch up your combat style at will.
Fallout 3 was pretty great. I agree with others when it comes to the environment, it gets old pretty quickly. But, I mean, it is a wasteland, I don't know what I was expecting. The DLC is pretty neat but not something I would pay extra for, so getting GotY on the cheap is the best idea, just in case you hadn't figured such already. Like M said, the lore is very interestng, so I even find myself reading about it online.
A lot of folks will say that they prefer New Vegas over Fallout 3, and I can see a few additions that may make Vegas more worth your dollar if you're just getting one game (Survival mode, weapon upgrades, whatever). The map is also smaller though (at least as far as I can remember, correct me if I'm wrong, guys), and the main story line has a little more oomph to it than in Fallout 3--but who plays for the main story?