I'm buying Descent after christmas but I was also thinking of getting Runebound. it sounds good but i don't like what I hear about the lack of player interaction. do any of the expansions have a lot of ways to interact with other players whether it be cooperating or disrupting each other?

prefably I'd like to be able to trip up other players on the way to the goal but a coop could work too.

The characters packs will be what you're looking for. They're introducing ways to hinder your opponent and benefit your hero. They add some new rules and some lenght to the game, but for me it's worth it.

Although I suggest playing some rounds without the characters decks until you're good with the basic rules so speed play up.