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