First: triode better?
Me, and everyone prefers Ultralinear to Triode here, You will find reviewers saying this and that. I think you can plan on your amp sounding great at 80wpc. You might find a particular type of recording that you prefer triode, but I am sure you will use Ultralinear primarily
at 7' high ceiling, I would not go for a big woofer,
these on ebay
should sound great, and if you want more bass, sub's it is. I recommend self-powered, stereo pair, front firing, located adjacent to the mains. Bass directionality comes from the overtones, 40, 80, 160, 320 ....
Sensitivity: 88. That is a bit low, you will be ok,
however, if you use subs, and you remove the low bass requirement from the amp, i.e. pre-out, crossover in sub, back to amp, amp now sending only upper bass, mids, highs to the b&w, the 80 wpc will be plenty.