Greetings, Electrostatman, I can see a storm brewing...
Strong opinions here.
First, your room is generous, but by no means so huge you have to get monstrous speakers. Most sizeable floor standers will suit you well.
Also, you may be getting the cart ahead of the horse; first give some time to the size and placement of the screen. Are you doing projection? Where and what will be equipment placement, including amps? Will you have any other decorative furnishings in front? Any built in cabinetry up front? These considerations can effect speaker selection! Where will you be putting your center chanel speaker, etc? This is why I suggest you do some reading in "Home Theater Builder" mag. and the like. Failure to plan, and you'll have an expensive OOOPS!
Go stand in the room and visualize for an hour or more. Think through every contingency and possible problem. Might save you a TON of money. Oh, and you may want to get your wife to stand there with you; could save a bunch of hassle later.
Maybe you need to decide which is far more important to you, two chanel listening, or HT. I have put the bulk of $ into two chanel, and about 15% into surround. I have never felt the surround to suffer, but I haven't expected the world of it either. I built the room primarily for music and secondarily for HT.
If you want a superb two chanel system, put the bulk of $ there. If that's your goal, it will be difficult to achieve with JBL, Klipsch, Definitive Technology and the like. Without disrespect to vendors, they're distortion-makers.They may sound ok when a car is crashing on screen, but turn off the video and listen to them critically and it'll hurt. As I said, Vandersteen, Magnepan, Revel, etc. will more satisfactorily achieve the sound you're chasing (don't misread me, other posters, I'm not saying they're the ultimate). Especially if you've lived with quality two chanel! If you've lived for two chanel, ignore this at your own peril.
I believe that fantastic two chanel is the base for a wonderful surround system. In fact, I will go so far as to say that one can have slight disparity between the higher quality mains and lesser quality surrounds and still be quite content. Make that decision based on the proportion of movie viewing you WILL do, not what you THINK you'll do. Just spending $28k won't make you have time to watch more movies.
If you watch a movie about once a month like me, who cares as much about the surrounds? But if you're living for the DVD player and you'll watch movies four times more than you'll listen to music, then you should think differently and place more $ on the surrounds. Just don't go and get all identical speakers for the 5 chanels! Then you'll really suffer when you listen to two chanel! Unless, of course, you plan on setting up some serious two chanel gig elsewhere...
This advice is based on combo of common sense and practical economics, and having learned the hard way of upgrading from low-fi speakers to lower-level hifi speakers. Practically speaking, if you want good quality through out your HT, then you'll need likely $15k for projection, screen, cabling, and components. Leaves about 8K or nine for mains and a 3k-ish for surrounds.
Oh, and we haven't even touched on cost of projector/television! That will skew everything also.
So, back to sqare one: What's more important to you, the sound or picture? etc...