Tim,
I understand your predicament! The reasoning and advice in the posts above is valid. Your choice should depend on why you do most of your flying (trips or pleasure). Let me add that while I know from experience that the 152 will handle the weight of your family, I also know from experience that it is not an SUV! You are not going to be able to load 2 adults and 2 children in a 152 and carry any real baggage at all beyond 4 toothbrushes, a razor and maybe a hair dryer!
I own and fly a 150 for pleasure, but will rent a 172 for those 2 or 3 times a year my wife and I feel the need to make a trip (just the 2 of us). We can then carry the needed luggage with more comfort, speed, and range, and we pay for it with the savings from the 150. Unless you expect to log more time on trips than anything else, the 152 is more fun to fly and will save you loads of money in purchase price and operational costs. Owning the 152 and renting the 172 gives you the best of both airplanes at the least expense!
