We went on the Land Shark tour mid-week, so it wasn't crowded at all. The water part of the tour wasn't overly-exciting; it involved heading out on the habor, around a buoy with sea lions on it, then back through the marina (i.e. it didn't match the description on the tour website that says "cruise the magnificent Santa Barbara coastline"). That being said, the city part of the tour was great - we saw the many historical buildings, the downtown hotspots, and beautiful views.
Our tour guide (Maddy) was excellent, providing information on local history, people, geography, and so on. She's an excellent speaker, also being a trivia host at the Brewhouse and the announcement voice at the SB Airport!
We'd recommend this tour if you need 90 minutes to relax while learning about the city, and especially if there isn't much a line to get on.