The parking is just across the street at Port Canaveral--closer than the parking at Tampa. Unless you have someone who is disabled or for some reason can't walk a couple hundred yards or so I would save the money and park and walk across.
What I do is instead of driving around and dropping the luggage off, then having to circle back around and park and walk back, I just go directly to the garage, park, roll my luggage down, give to a porter along with a $5 or so and merrily go on my way.
It's close enough to easily walk: if you have a good throwing arm, you could
probably hit the ship with a rock from the garage. ;-)