When your chosen themes accommodate one another, you can create a unifying theme. Think of 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 decide to do an around-the-world theme as part of your living room; this is sort of a miniature version of Disney's Epcot. You may incorporate Asian tropic plants, dragons and samurai swords that would incorporate all three themes. The point is, regardless of the themes, there is certainly common ground to be found.