archea - i had the EXACT same quandry. Every time I'd go to my brother's house to test subs, I'd come home wishing my basement wasn't on a concrete slab.
I considered a platform, I considered butt-kickers.
The solution is actually much more simple IF you have multiple subs and room for it: place one sub nearfield immediately behind your seating, facing your seats.
I put my A7s-450 in that position, put the crossover on the amp at 50hz (anything higher is too localizable) and set it to run 6db quieter than the two subs I have up front next to my front mains. Those subs I crossed over around 150hz.
That setup allows me to enjoy the couch-shaking (and believe me, it is every bit as awesome as being on floor joists) effect without feeling like the bass is coming from behind me, I still get plenty of mid-bass slam from the front subs AND to top it off, the couch-shake effect is timed much tighter to the actual timing of the frequencies being played, so it's even more satisfying.
If you have circumstances that allow, give it a try.
Quit readin my signature ya stupid signature reader.