Remember you can fast travel, I know one person who didn't find out about it until they had finished the game and spent a week tring to get into rivet city and another who kept forgetting to use it If you are after achievements or trophies then at some points it's best to save and take the action you don't want for example at set levels you can get 3 achievements or trophies for having good, neutral or bad karma, another would be Megaton, save, blow it up for the reward then load save and disarm