Even though a 'luxury' brand name isn't important to you, the first recommedation that came to mind is the Acura RDX. It's technically considered a 'compact' luxury SUV, but it's on the large end of the compact size class. It's actually less than 6" shorter than your Nissan Murano. The interior space is vritutally identical with the RDX having 103 cubic feet vs. 105 for a Murano. So it's very similar in size.
There are three primary reasons that I think the RDX could be a good fit for you- Reliability, Size and Performance. The Reliability and Durability are both excellent, as expected from Honda/Acura products. The interior is very comfortable for four adults (it actually has 2" more rear seat legroom than a Murano). The front seats in general and the driver's seat in particular are comfortable even after several hours on the road. Best of all, there's a good ol' 279hp Honda V6 under the hood! It's good for 0-60 times in the low 6-second range, very quick among the SUV/CUV group. The 6-speed automatic almost seems like it can read you mind because it's always in the right gear and you'll never catch it flat footed. It's always ready to pass, merge or run for hours on end at 90mph on the rural interestate. =)
Another idea I wanted to toss out, though it may not interest you, is the new Mazda CX-9. It's a bit larger than your current vehicle (a 7-seater, although it makes a great 5-seater with a huge cargo area), but it handles and generally feels much smaller. It also has a turbocharged 4-cylinder, but the engine is tuned for 310lb-ft of torque at 2,000rpm, so it feels like a MUCH larger engine. The power delivery is so smooth that I had to look under the hood just to make sure it wasn't a V6. (BTW, in the interest of full disclosure, I own a previous-gen 2012 Mazda CX-9 and I love it). It's just a lot of car, both in size and features, for the money. The interior is near-luxury in terms of material and assembly quality and fuel economy is among the best in class.
My final suggestion is a bit 'safer' (some might say boring) and the reliability probably won't be any better than avearage- the Ford Edge. It's the only domestic-branded SUV/CUV that I could ever imagine buying. I would skip the standard 2.0L EcoBoost 4-cylinder for the 3.5L V6 though.
Good luck and hope this helps!