This has a lot to do with where you live (I live in Tyngsboro, right over the border from Hudson). Bathrooms almost always increase the value of a home. And if you can find someone to build you a bathroom for 5 grand, call him back immediately, before he changes his mind!
As for the basement, just be careful. As someone mentioned below, finishing your basement for $30k will probably not add that much to the value of your home, but you dont have to spend that much. You can probably do it yourself for around $7500. Or you can call one of those basement finishing companies. Just don't go crazy if you're doing it to increase your home value.