I didn't bother to look up current prices on your speakers and sub, but I know that the difference between those and $2500-3000 is not much (if anything left at all?). If you just said so from the beginning you could have saved me from typing out thousands of words, haha. Anyway, you can easily cross out the following possibilities: anamorphic, tab tensioned, dual displays, SI BD.
Actually, this is easier than I thought. Just get the biggest Pana (or Samsung) plasma you can afford. If your budget does indeed "fluctuate" in the future but for the better, then adjust the plasma choice by PQ as second criterion. Done.
Now you have plenty of space to put the speakers. Pretty easy.
Of course if this was my room, that I had this newfound freedom to control my light, was not allowed to compromise the length of the room, then I would just sell my speakers, and get in walls so I could have my AT screen. Because I could make a pretty big one for not much (only $21 per linear foot), and I'm pretty sure DIY in walls should not be more expensive than most BW speakers even after eating a bit of a loss.
Because speakers are no longer possibly constrained by the width of a screen, and that you have 12' to play with theoretically, you can just play around, experiment, even measure. Honestly, there isn't much to think about. You CAN get some ghetto PJ, throw it up on a blank wall, but it won't be worth it. Even I would go for the plasma in such a case, without even half blinking.
Remember, if 2.5-3k is the full budget, then you're really not going to like how much the bulbs cost, and how quickly they die.