In that budget and criteria, I would be looking at the Denon X4300 deal that AcuDefTechGuy linked to.
If you are into content that likes heavy bass, I would go for two subwoofers and a pair of bookshelf speakers. If you want tower speakers, just set the bookshelf speakers on top of the subs, and viola, tower speakers, but now you have tower speakers with bass capability far beyond regular towers. That is essentially what many tower speakers are anyway.
Lots of good speaker and subwoofer manufacturers out there, look at Revel, RBH, Hsu Research, SVS, Ascend Acoustics, Outlaw Audio, Rythmik, JBL, etc. One inexpensive floor-standing speaker I quite liked was the Fluance Signature towers, very nice sound on those, and powerful bass capability as well.