LOt's of good sounding smaller monitors that fit that price range w/sub. Anyting from The newly released/reviewed(HT magazine) Infinity TSS750 system at $750 w/sub ($650 at Circuit city), to using NHT super Zero's/SB1's and sub and such would sound as god as you wold want from and HT receiver based system! You can tinker with other choices, but you won't get much improvementon the abilities there.
OH, BTW, for what you are after, it won't make any difference with your 20 ft ceilings!....very fogiving of speaker options there. Find a good sound, right budget, good looking/well built montor and large enough sub for your room/budget, and your done. the two or so recommendations I gave you are fine sounding, good looking, well built, highly reviewed, and solidly built gear. good luck