accomodation in luang prabang and vang vieng

Hey Guys,
heading for Laos next week. trying to find a cool spot to stay in luang prabang and another in vang viend. anywhere cheap, clean and central with common area / place 2 relax n meet other back packers. there s4of us altogether so dorms or double rooms are rooms are cool. also what good adventure stuff is there to do in both places besides tubbing (sounds nuts cant wait). any tips wud be great
cheers
Ellie