I'm not a big fan of watching movies over and over again. (but I will watch favorites frequently over the years). However, there are a precious few that I have watched hundreds of times without ever tiring of them.
Star Wars (the original trilogy), because it has everything: romance, adventure, mysticism, aliens...
I, Claudius (BBC mini-series) I'm a fan of the novel, and I love this series. The acting was superb, the story is intriguing. And it has John Hurt, my favorite actor.
Rocky Horror Picture Show--I don't even know why I like this movie so much. But it always puts me in a good mood.
Strange assortment, huh? These are my feel good movies. If I am going through a creative slump, watching one or all of these will usually give me fresh inspiration. They are like old friends that never fail me.