The Ascends are good advice. I would also give
these guys a close look, they are $650 shipped. They have very good extension for bookshelf speakers- 43 hertz! That is probably due to their size, and slightly larger than average woofer diameter of 6.75". They are 8 ohms speakers too, so you can use them with any amp or receiver. They are heavy suckers for bookshelf speakers, at 53 lbs a pair, so its good that shipping is free within the 48 states.
Much like those are the
Aperion Intimus 6B, although they are just a bit over your budget at $690 shipped. They are also larger, heavier bookshelfs, they have good extension but these are quite insensitive, with a sensitivity of 82 db. I would want to have a fairly powerful amp if I were to ever use these. Now that I think about it, these might not be the best speakers for your situation unless you were going to use a more powerful amplifier.
These might be good for you, if your amp can handle the 4 ohm load. I seem to remember reading that they have a pretty steep roll off at 80 hertz though, so I wouldn't use them without a subwoofer (personally though, I wouldn't use any bookshelf speaker without a subwoofer, but that is due to my particular tastes).