1.Additional amplifier features- Who doesn't like to play!
2.Additional wood veneer choices like cherry, bird's eye maple, ash, rosewood, piano black- You could have the best sounding sub in the world, but if your wife doesn't like the finish, you're going to wind up putting it in a place where nobody can see it, or hear it the way it should be heard!
3.Slimmer profile subwoofer model- Similar to #2. Most women I know hate subs ("big, useless, cubes"). A smaller profile or intriguing design would go a long way to bridge the gap.