What really works in these bigger rooms? Looking for something with better bass detail than a pair of extra subs rumbling 60 hz and under.I don't know what subs you've been listening to, but that is hardly a fair description of what the better subs do these days.
For that sized room, some powerful articulate subs are exactly what you need. I'm not sure what your budget is, but one or two JL Fathom F212s would do the trick. They are linear, dynamic, deep-reaching, and most of all fast and articulate to blend seamlessly with the main speakers.
Another good candidate is something from Velodyne's DD+ series.
The articulate, musical subs generally have sealed cabinets, sometimes with passive radiators, light and rigid diaphragms, massive magnets and frames, and inert enclosures. Many have tone shaping software for a better fit to the room.
I have a modest pair of floorstanders that were a bit small for my listening area, which is open architecture with a cathedral ceiling. I added a pair of (now out-of-production) Mirage MM8s. They aren't made to plumb to 20 Hz, but with 1200 watts peak and 8" aluminum diaphragms augmented by matching passive radiators, they fill the 32-60 Hz region perfectly. I had to work at placement, phase, crossover and level matching for 2-3 hours to get it to work well, but that was well worth it. I didn't want to give up the small towers because they did so many things well, but didn't put out the bass to energize the space. Adding two compact extremely fast subs did the trick. These things are anything but woofy or muddy.