RE: GPS around Seattle
BTDT, I live just north of Seattle and have lived in this area all my life.
The GPS will try to take you onto the ferries so if you don't want that you
have to be aware.  The GPS units I've used have had an option to 'Avoid Toll
Roads' or some such but if using a GPS in a rental car the user is not going
to be familiar with the various options or may not even have them.