Making the best of mediocre speakers

Why not try conventional speakers with wall mounted brackets.

You nailed it...this is not going to be a perfect listening room. So, make your decisions based on this. Your limitations are going to be your speakers...so dont spend the majority of money there. Get cheap in walls with a cheap sub. Spend your money on good components. If you move in the future...you just going to throw money down the drain with those in walls, whereas the components will be there for a longer time. If you want an audiophile listening experience, get some good headphones and a good heaphone amp as suggested above. Just prepair yourself for the "honey...are you going to sit there with those things and not pay any attention to me" comments. Which, at that point I would remind her about the inwall fiasco.

Consider ceiling speakers with tweeters that can be aimed at the listening position. I am very happy with Klipsch in ceiling speakers. They don't require much power, so a tube or class A SS amp will will be sufficient.
You really need to convince your wife that a subwoofer is a wonderful end table. You can even put a plant on it!

This may be a dead issue, but I would revisit the question of whether you might find a way to use conventional speakers in the room. I have a pair of Salk SongTower QWT finished in Hawiian Koa wood. My wife, who has rarely seen a speaker that she likes in a room, okayed these. She treats them like pedestals and displays something on top. I have my SongTowers at one end of a long series of open rooms and they project throughout the open space quite well.

The SongTowers received very good reviews, have a small footprint, can be custom finished to blend into any decor, are flexible in placement and have great dispersion. These sound good to my ears even when placed in less than ideal locations. You might try a SongTower or variant thereof along each wall.

My suggestion would be to contact Jim Salk at salksound.com. He might have some additional suggestions for your difficult room. Since he custom builds speakers, he may also be able to offer a speaker you could mount on the wall or place in an acceptable location as an alternative.

There is a forum on audiocircle.com for Salk where you might post and get additional suggestions.

My frst choice would be a nice pair of full range speakers , Maybe something nice looking like vienna Acoustics etc.

If that is not possible There are many inwalls that are excellent. For example Speakercraft makes expensive in walls that you can get which also have two enclosure options, foam and metal. The enclosures make a huge difference.

Lastly my advise for the best system is to get the best source. A better CD player or Dac if your doing a music server will make a bigger difference that the electronics once they are past a certain point.