I'm still on my first play through. I tend to play through these games using a character type or personality. I screwed up naming my guy so he's "The Courier". I've been going through the game playing a mildly "good guy" game, but not a saint. He simply does what he can to help facilitate his goal of revenge. I kind of envision him as a Clint Eastwood/Toshiro Mifune type character. He's not overtly good, and has no problem blowing someone's brains out to solve a problem but if he see's a problem he can't help but intervene. Making allies of the NCR is a good way to make the wasteland easier, but now I've got the idea of taking over the Strip to consider...He's also had a problem with the Legion since stumbling into Nipton. That kind of thing changes a man.
One thing I've found, is every time I'm in Vegas I end up not playing much. I think there's something about the Strip that I subconsciously just do not like. Right now I'm trying to do the White Glove Society, and I find I have little desire to play. I could just abandon the quest for now...but I'm already in there as it is. :(