Food service is available on almost all routes, beer and wine on some.
The bike surcharge is 60 cents from Seattle to Bainbridge, Vashon, or Bremerton. The car-ferry trip to Bremerton takes an hour. The Seattle-Bainbridge Island run takes 35 minutes on a jumbo ferry. If sightseeing is your objective, take the Bremerton trip. It's a bit longer, but the scenic ride crosses the sound, skirts the south end of Bainbridge Island, and passes through narrow Rich Passage into the Kitsap Peninsula's land-enclosed Sinclair Inlet.