Don't want to go too far off-topic, but what I don't like about Fallout 3 is that it's so depressing in tone and image. It really gets to me in that regard after 8 hours or so.
So what I did to handle that is I started to cheat like crazy and killed everyone, and the game was fun again for as long as that lasted..
I really dig Fallout 3, but only to a certain degree.
What The Witcher really does better from that PoV is the game has fun with itself. And it features a world I enjoy fantasizing about. FO3 - not so much.
For example, compare the bar scenes in FO3 with those in The Witcher. In TW, the dudes in there are really having a good time, partying, drinking, making music, fighting and playing dice games.
In FO3, they sit at the bar and stare into their glasses, and melancholic 40s music drags 'em further down.
And that makes perfect sense in that world, but because I don't enjoy it, I acknowledge that setting being in line with how the world works, but don't get anything else out of it except for an urge to mess the place up. Which is, and I'm sorry to say that, something I don't want to happen in my RPGs. I really want pure immersion, not the feeling that I need to break it in order to get over the mood.
Same with the night scenes in both games.
In TW, you have bandits lurking on the streets, drunken old men snaking home, hookers switching legs at the corners, dogs searching for something to bite, patrols checking the back alleys, it's a living environment.
In FO3, there are no streets, basically, the people that are out are likely to shoot at you on sight, it's dark as fuck and you just want to go from place A to place B to get it over with.
In TW, I had no problem walking drunk from a party to the place my buddy the dwarf lives. In FO3, I'd probably wait it off to be able to handle a deadly situation.
So FO3 is survival-oriented to a degree that it almost becomes threatening, but in TW, the world gives me the feeling that it's not the end of the world if I let go a bit.