My family gets completely crazy over this game. We're all incredibly competitive players, and we like to cut stupid deals (like three pieces of property in exchange for $500 and three turns of land-on immunity). We also like to put tax and house money in the center of the board to be claimed at Free Parking, so that's another element of insanity in and of itself.
I usually play as the car. It's my favorite piece, always has been. I'm not completely sure why.
As for property, I try to get the light-blues (Connecticut, Vermont and Oriental), the reds (Kentucky, Indiana and Illinois) and the yellows (Atlantic, Ventnor, and Marvin Gardens) because it seems like that's where people land the most when we play. Seriously, I once played a game where most of my income came from a totally built up Kentucky.
We own the original version as well as the modern "Here and Now" version that uses updated properties, credit cards instead of cash, and denominations in the hundred-thousands and millions instead of hundreds and thousands.