In-ceiling, can you put yours heads together to help me out?

That was the only place I was able to put mine due to room/house design. I bought directional/aimable if that's a word. I built boxes and insulated them to make sure they fire downward instead of back as well.
They sit just about three feet behind the couch on an eight foot ceiling and sound pretty nice and do a good job of surround as well.
My front and center speakers are in-wall as well. Powered sub just sits there, but I did run the speaker wire to the opposite side of fireplace and installed banana plugs. I didn't like the idea of box speakers hanging on the wall which may have sounded better because of being able to aim them better, but i'm pretty happy.

and you are dead set on building the enclosure yourself, you'll have to research the drivers, and their recommended enclosure size. I've never built speakers, but you must particularly find the Q of any driver. Don't ask me, ask others.

Yes, match the fronts. Towers will be umpteen times better than the in-walls, and your money goes further. Even if both were at the exact same price, the free standing gives you bang for buck.

The best is three towers in the front. Very few do this. I've been ranting and raving for a long time about this. Even a few times just this past week at Audioholics, where I have a 1000 posts, or at AVS where I also have a 1000 posts.

Now, if you have a large DLP sitting on an AV rack, you can't, understood. If you have a flat panel mounted on the wall a few feet high, you absolutely can, and IMO absolutely should.

get a modular rack for $200, and put it anywhere you want, just not up front. Even the closet if you want. A URC (extremely reputable) RF-20 remote + blaster is only $75 last I checked.

By having the identical tower, you will be:

- perfectly matched as matched can be, in all speaker characteristics
- even plane of tweeters/drivers for perfect and even panning
- completely bypass horizontal lobing issues inherent in a horiz mtm design, which usually means a sweetspot at less than 20 degrees. (towers are roughly at 60 deg). Also, the horiz cabinet means vertical dispersion as opposed to horiz dispersion. Sound likes to travel along the path of least resistance (smallest dimension), so to speak.

If it indeed must be horizontal, the best designs will be such as top mounted tweeter (ie B&W), WTMW (ie Revel, AV123), or coincidental (KEF).

Now, if you have only one loveseat, for 1-2 viewers, not as big of a deal, assuming you sit straight on. If you have more than one couch, my suggestions just only regarding center design will benefit you greatly.

Let alone the matching and pans. Oh, you also gain better video immersion since you don't have lights up front anymore.

I've talked about this 100 times at this forum alone.

and even if it were true, I would bet good money that the correct enclosure size will be vastly more important.

I am not. The rear ceiling speakers are 6 inch round and were only like 3 inches deep. I just cut 2x4s long enough to box in the joist, added a little more insulation to them and I think 1/2-3/4 inch ply on top of that. The speakers are not centered in those due to I positioned the speakers evenly in that portion of the ceiling for esthetics. So one may be closer to center than the other because I have a joist built house.
Maybe if I were building a house I would pay close attention and be able to specify perameters for such luxuries. But since this home was already built, that was out of my control. I had to work with what I have.