I park on the sidewalk if I have seen a precident for it. For example, Best Buy always has bikes parked in front of it.
I park in the striped part of the handicapped parking area when available. With the size of these areas and the size of the bike, I am not keeping anyone from getting a wheelchair (or motorized scoot) in and out of a van.
Otherwise, I park in a regular space as close to the building as possible. I don't leave my helmet very often, since I had one cut off the bike last year. (They ruined the straps, which was dumb.)
When I park in a regular space, I don't pull in as far as I could, so that people don't whip into what *appears* to be an empty space, only to end up hitting the bike. If my tail is even with other cars, the bike is more visible from further down the row.