That's a big room, and a living/dining/family room.
-You need a bigger sub.
-Dynamic range is your friend, so towers are definitely justified, but not absolutely necessary.
-Ceiling speakers are not meant to be the main channels, but fine for atmos or surround channels. (The band and the sound system at the club aren't up on the ceiling, so neither should your main speakers be, if creating a convincing facsimile of the show at home is the goal.)
-Don't go crazy trying to achieve ht perfection in there. Do choose your speakers and sub wisely and you'll have a satisfying 2.1 rig.
-Get the biggest, ugliest, least WAF speakers possible, as a test of her commitment to you and your audio proclivities. (/s...sorry, couldn't resist.)
I had a *very* similar room situation, where a 3.1 rig really enhanced sports and movie viewing pleasure, and a single corner loaded sub worked pretty well. We had the tv spanning the corner where the sub is located in your layout, with the tv stand credenza creating triangular spot behind it for the sub. This effectively hid the sub from view, which was good for WAF. The left and right speakers were wall mounted, several feet out from the screen on each side, positioned so the axes crossed behind the mlp. The couch occupied that mlp, out in the middle of the room, oriented diagonally and directly facing/parallel to the the tv screen. Not only did the couch enjoy a very nice sweet spot, but the areas to the rear of the room also had pretty good coverage and enjoyable full range sound, perfect for a multi-use living/family/rec room. We did eventually add some rears, which your pre-wired locations could accommodate similarly, but it was pretty solid even as just 2.1 and 3.1.