Funny you should ask, and i'm surprised not a lot have commented on this question considering that there are sooo many activities you ca do in Paris. it really depends on what interests you. if you're into art appreciation, then there are quite a few great museums you can go and visit in Paris.if sight seeing is your idea of fun, my favorite would be the cruise on Seine river, and may i just say that this cruise is a must activity! aside from that there are still a lot of things you can do, you just have to find what interests you. heck you can even visit the sport center if you want!