i never worry about somebody breaking in or stealing the car - that is what insurance is for - i rarely even lock mine, so as to minimize damage in the event of a break in - i used to have a sign on my mg that said "it's unlocked - take what you must, but please don't hurt the car"
i think a car cover on the car at the airport is brilliant - every time i park there i end up with scratches from some knothead who think his jumbo garment bag is a carry-on, and tries to squeeze in between cars, scratching up the side of mine
just get one that has the cable lock that goes under the car - then it will require a tool to get in, making it less desirable of a target - think about it this way though, it's no more secure than the soft top, but will at least keep scratches off of it
as for which one, i have 2 - one water tight and one nice and soft - they are used accordingly, depending on the situation
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating
www.968forums.com
"It isn't nearly as expensive to do it right as it is to do it wrong."