When your chosen themes accommodate one another, you can create a unifying theme. Think about this: your spouse wants an Asian theme, your teenage daughter wants a gothic theme and you want a tropical theme. In such varied combination you may elect to do an around-the-world theme with your living room; this is sort of a miniature version of Disney's Epcot. You can incorporate Asian tropic dragons, samurai and plants swords that would incorporate all three themes. The thing is, regardless of the themes, you can find common ground that can be found.