The best saying that I have heard regarding these things is if it Fly’s, Float’s or Fu(k’s then rent it!
Flying is definitely covered in this, it makes owning a boat look cheap. If you are going to do a heli then the budget is gone and you better be able to afford the boat and the flying!
If you want to fly don't trust a piston engine if you are in a single engine aircraft, that is if you are ever going to have any one you care about that is going to fly in the plane. Either go multi engine or turbine, turbine is preferable. Also train, train more and then train some more. I would suggest that you get at least your MEI and CFII, after all of your training fly at least once every two weeks! Also suggested is unusual attitude training, and aerobatics if you want to have fun.
Now on the fun part, a Pitts S2B will give you a rush that can be matched by no boat. When you are turning and burning at 4-6G’s it is a riot!