Oh the joys of having a basement

. I'm assuming none of those toys will be used until spring. Can't you store them outside covered in plastic? Or will they fair worse in the rain.
You are going to need a good cover anyway, there is no way with kids coming and going with bikes and minature cars that you won't get some good scratches on the Boxster. I'm thinking you may get more damage that way than just parking outside with a cover.
And if you are buying a used car with some good wear and tear on it already and just want to drive it and not look at it...well then it will be ok outside cover or not. I enjoyed both driving and looking at my cars, so for me it was garage all the way but then I have a basement for all the stuff that folks normally put in their garage.