I also own a vacation rental. It's impossible to underestimate the level of care (read damage) tenants provide (read inflict). I would get a used AVR or all in one, w some party-hardy speakers and lock the good stuff away for your own use. Maybe a used pair of NHT floorstanders. There are lots of replacement parts available and they actually sound pretty decent. The great room in my house is not nearly as big (L shaped, maybe 25 x 20 with a 10' notch cut out) as yours and I use an NAD 5.1 all-in-one (L-70, IIRC),4 NHT Superones, a Supercenter and an old NHT 10" sub. I am always pleasantly surprised when I get to listen after the tenants leave. That rig probably does not have enough oomph for your space, but if you scale it up appropriately, it should do just fine for parties, background music, HT use. I keep a small BR system locked away (93 dB Zhorns, Bering micro-Zotl, Sony S7000 and HD-650s) for when I need my audiophile fix.