Am spending a weekend with a guy that really likes me. How do I behave around him?

This pretty much depends on how much you like him. Is he just a friend in your view or something more?

If he is just a friend then it can be difficult, as I've been in his position. He will probably think that you being nice to him means you like him the same way he likes you. Speaking from experience it can be very hard for him if he really likes you and you don't feel the same. I guess the best solution is just to be honest with each other and tell him how you feel. Hopefully no matter what you can still be good friends

If however you want to more than friends then I'm sure things will work themselves out ;) Don't just rely on him to make the first move. Guys are pretty hopeless at reading subtle signals so you need to make it obvious what you want.