Sub options
I have one of the SVS SB12-plus subs in my living room HT. It is compact, looks good, and sounds good. However, don't expect too much output below 20 Hz. If size and asthetics are important factors, then 2 of these would work great.
If the want to "feel" the bass in your dedicated movie room, then consider dual MFW-15s or other large ported subs for your room.