HT Area? Is your "ht area" open to other spaces/rooms? You sub(s) won't know the limits of what you define ht area.
That said, most likely any pair of subs you picked will be able to fill and pressurize very large spaces
Lets start with my least favorite and start going up:
-eD A7-350: 15" sub; 1300w amp; 16-100hz $1,440 ea
This one has all the kick and extension you would ever want or need, but eD subs are not very transient - thus not perfect for music, but still great for HT
-Hsu Vtf 15h: 350w continuous/1400w short term; 15" sub; 16hz $879 ea
On the opposite - very musical sub, just don't have strong low real extension and lacks in power.
Now these two:
-SVS PB12-Plus: 12" sub; 800w amp; 16-150hz $1,399 ea
This is a great sub in all aspects ... but
-Rhythmik FV15HP: 15" sub; 600w continuous; 14-90hz $1499 ea
This is sub is better and basically it's on the level with SVS PB13-Ultra
p.s: Most vendors will provide discounts if you order two if you ask