I have owned a model M 172 and now a model F 150 and...
IMHO: The 172 is a more versitile, comfortable airplane and costs no more to maintain than its smaller sibling. Fuel burn isn't much different at similiar airspeeds but of course the 172 will go faster if you want to feed it. I would't even consider the smaller airplane for a growing family of 4. You'd find yourself flying alone or not at all having to worry about comfort, load capacity, and performance considerations. As for buying a 152 and renting a 172...WHY? (sorry fellas) that just doesn't make any sense to me. Buy a 152 and rent a 206 now and then, sure, but the difference in cost of ownership between the two is a Reallybignumber! 152 vs. 172 = A few bucks vs. Lots of advantages.
Of course, either way, you are required to remain a member of this club!! <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />
