If you don't have the space, the budget, or the inclination for big floorstanding speakers, go with something a little smaller. The most popular speakers for home theater use are bookshelf speakers, so named because they're small enough to fit on a bookshelf or a stand. Speakers such as the Klipsch RB-15s are great space savers and blend unobtrusively into just about any room.
Because you can't fit really big speakers into a small box, bookshelf systems are limited in terms of the number and size of speaker drivers. Most bookshelf speakers are two-way systems, containing a tweeter (for highs) and a midrange driver or midsize woofertypically 8 inches or less. But the right bookshelf speaker design can deliver surprisingly good sound, with more than acceptable bass response. Of course, you can and probably should supplement a bookshelf system with a separate subwoofer, especially for home theater use.
What a bookshelf speaker gives up in bass, it makes up in sound imaging. Smaller speakers are better at providing a distinct sound stagepinpointing sounds in space. Bigger speakers can get a bit "mushy" in terms of where sounds are positioned in the sound field. Smaller speakers put sounds in specific places, for terrific imaging.
Smaller speakers also tend to be a bit more neutral in terms of fidelity to the original sound. Many large (and expensive) floorstanding systems color the sound to some degree; true audiophiles can easily tell one speaker from another by its sound characteristics. Bookshelf speakers are less likely to color the sound, and thus deliver more neutral reproduction.
As with floorstanding speakers, the more money you spend, the better the sound you'll receive. And the best bookshelf systems deliver sound practically indistinguishable from what you'll get from a similar floorstanding system.