If 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 opt to do an around-the-world theme inside your living room; this is like a miniature version of Disney's Epcot. You can incorporate Asian tropic dragons, plants and samurai swords that would incorporate all three themes. The thing is, regardless of the themes, there is certainly common ground to be found.