I would second Burbunny - the port area is not the most pedestrian friendly area...
I think that you have a number of choices:
- leave your travelling companions and luggage at the pier and walk to collect the car, then come back to the pier pick them up. I have no idea where on 17th St it is though - can't remember seeing it - so could be a LONG walk (looking on there site - and getting "driving directions" - it appears to be a 4 or 5 mile walk!!!).
- get a cab to the Bydget depot on 17th St.
- rent a car from one of the airport based depots (there is a Budget depot there) and take the rental car company's shuttle from the port to the depot (free and frequent) - this is what we do.
- check to see whether Budget on 17th St has a shuttle. Would imagine they do...
Would recommend wither cab or renting from the airport depot and taking the free shuttle.
Could luck and have a fun trip
Boo