The Cessna TR182 is what I stepped up to from my C172. The RG combined with the turbo and built-in ox system make it very fast for a Cessna. I cruise at 162 KTAS at 10k to 12k feet like clockwork. I carry myself, my wife, my kids, 50 lbs of bags, 30 lbs of "stuff" and full fuel. I can fly for 5 hours with IFR/night reserves at the power setting required to achieve 162 KTAS. That means I could fly from Denver to Houston non-stop if we had the bladders for it.
The folding gear makes a big difference in drag and enables better efficiency in flight with the trade-off of higher insurance (mine is $1400/yr for a 375-hr pilot with 150 in type. It was $1700/yr the first year. Hull value is ~$110k for mine) and somewhat higher maintenance. Mine was rebuilt by a previous owner so that was baked into the purchase price.
If I want to go even faster or get above wx I can climb as high as FL200, which I have done. It is a hike to get there, but once there you can get 175 KTAS (no more than 120-125 KIAS though - so temps must be monitored) in cruise and much more on initial descent. I regularly see over 200 KGS on initial descent from up high with no more than 160 KIAS (179 is Vne). That is fun.
And it is a Cessna so everyone can work on it, STCs abound, the cockpit and systems will be familiar to a 172 driver. Just have to learn the new stuff: rudder trim (easy), constant-speed prop, gear and cowl flaps. Not that big a deal.
If you do get a complex airplane, expect people to ask you to lease it back to the nearest flight school. The 10-hours of complex required for the commercial ticket have become a real problem since practically no one makes RGs any longer.