First, welcome to Audiogon!
Here's the deal. You're simply not going to be able to get that "sweet spot" of sound with in walls. Tell the wife you not only have to get the in walls, but you have to install at least 10 separate tweeters in the ceiling to get any semblance of stereo sound, so you'll need another amp too. Might as well go for a few more sets of in walls while you're at it. For the sub, you'll need something like the Eminent Technology Model 17 to make up for the lack of bass from the in walls.
When you present her with all this, a set of monitors & separate sub will seem like a much better compromise.
Here's the deal. You're simply not going to be able to get that "sweet spot" of sound with in walls. Tell the wife you not only have to get the in walls, but you have to install at least 10 separate tweeters in the ceiling to get any semblance of stereo sound, so you'll need another amp too. Might as well go for a few more sets of in walls while you're at it. For the sub, you'll need something like the Eminent Technology Model 17 to make up for the lack of bass from the in walls.
When you present her with all this, a set of monitors & separate sub will seem like a much better compromise.