I've just finished setting up my first real listening area (tv room), with some equipment I've been collecting from Craigslist and garage sales. Right now I've got:

Panasonic sl-h301 turntable with a new higher end audio technica needle (actually sounds really nice once the tonearm is balanced> 

or Airport express optical out >MSB link DAC>

Kenwood Kr-4070 tuner/integrated amplifier>A

KLH AV 4001 Floorstanders (12inch woofer, 5-1/4inch mid with a ~1inch tweeter. 

>B Dayton audio B652 bookshelf speakers on 24" weighted stands. 

When listening with the Dayton's the sound is spacious and great (for $30 these speakers are really amazing, I replaced the stock tweeters with Dayton Audio 1-1/8in silk dome tweeters ~$22 each). They lack in the low end sub 80Hz or so, but they image well. I have them set up beside my flat screen, about 6ft apart, 1 1/2 foot from the back wall and 3ft from the side wall at the closest point, toed in towards my listening position about 7ft away. I'm pretty happy with the way they sound,

 but for really pumping up the volume I invested in the KLHs ($80 for the set in absolutely pristine condition). I can tell they aren't high end speakers, but tonally they sound very clean and balanced, and the crossovers sound like they are fairly high quality (though I'll probably replace them along with the tweeters which are a bit bright, I have a soft spot for silk domes). They are set up a la the Daytons, just outside them (slightly farther from eachother), toed in to my position. I have them farther from the back walls, about 2-1/2ft. 

I want more spacious sound, I think the problem is my room/environment, it needs to be larger. When I move the speakers farther from the wall (about 4') they sound a lot better, but this intrudes on the use of the room so it's not really an option. So I'm wondering what are the tips/tricks/room treatments I should try out to get more open, spacious sound in the area I have? 16'x16'