If both free-standing and wall-mounted (or even in-wall) speakers are all verboten, then maybe you are a good candidate for the Yamaha YSP-1 "sound processor", which produces a reasonable facsimile of 5.1 sound, out of a single box that looks more or less like a long center-channel speaker. You need a fairly regular-shaped room, as the front L/R and surround L/R channels are "beamed" off of walls. Also, to get good bass you still need a sub, but that can maybe be hidden someplace. Of course, you also need a place above or below your TV or screen to put the YSP-1 itself, but other than it and the sub, there are no front speakers and no surround speakers to deal with. List price is somewhere around $1400, but I don't know what a good discounted price would be.
Alternate plan B would be to try and convince your wife that speakers can be like fine furniture pieces - focus on speakers with cabinets that match the decor of other furnishings in the room, in terms of color, wood type, etc. It would be nice if magazines like Architectural Digest and other Home decorating magazines would show home theater set-ups, instead of them only showing up in dedicated home theater magazines. But interior decorators and designers by and large haven't made the mind-set leap necessary to incorporate the needs of a home theater into their interior designs. (In contrast, home architects ARE starting to pay more attention to room layouts that are better for home theater - and you are also seeing new model homes with decent set-ups, either real, or with reasonably-placed cardboard fakes..) Ten or 15 years ago the problem was finding an armoire or cabinet that was deep enough for a 32 or 36 inch CRT. Now it is finding a room with good places for 5-7 speakers plus sub, plus a good location for a big-screen TV and/or flat panel display. I think that a large percentage of plasma and other flat-panel sales are due to the phenomenon of the best spot in the room being right where the fireplace is, so now you can put the TV above the fireplace. Eventually the architects will put the fireplace in the corner, so the TV doesn't have to go there. And then the TV will be the "focal point" of the interior design for the room, and not the fireplace.