Like robatthelake, I'd never even noticed that I don't think our coach has any 2-way switches. I don't think I have any switched lights that cover enough of an area to really need them.
My only complaint with wall switches was in our 99 Tradewinds which didn't have any at all. The only switches were on the ceiling lights themselves - not really a problem for us but my 7 year old couldn't reach any of them which was a problem (e.g. if he went to the bathroom during the night or early in the morning, he couldn't turn on the light).
One absence of 2 way switches I have notice (thankfully not on our coach) is for the water pump. A couple of years ago, a neighbor bought a new Class C (I forget the brand) and the light for the water pump was always on. Turns out that ever water switch is a one-way and is in parallel so if you want to turn off the pump, you have to turn off every switch - after spending an eternity trying to get them all, we finally noticed there was one in the outdoor shower compartment (which is in a separate compartment from the water hookup on his coach).