Before I bought my LRB, which is a P172D with 180hp and a CS prop, I had figured that my usual missions would be me and dog, occasionally me and a friend or two or once in a blue moon fill the seats, often local, sometimes cross country, once in awhile into the back country. That's exactly what it has turned out to be.
For camping with dog or camping with a friend, the airplane is pretty full, not too close to gross weight, but certainly really close to "gross room". Cross country in the winter, between baggage and engine cover etc., it's again close to "gross room".
For my kind of flying, a 2 place wouldn't work. But others' experience/needs will vary. I figure the additional 3 or 4 gph, even at current fuel prices, is worth the flexibility of being able to meet nearly 100% of my "mission" requirements.
Cary