I have taken just about every out of town visitor I have had on the Argosy Lakes Cruise leaving out of the South End of Lake Union. This is basically two very pleasant hours on the lakes in the summer. Highlights include Bill Gates' house and the Sleepless in Seattle House. That stuff has gotten pretty old for me, but the two hours out in the sun on the lake while my visitors titter about the sites is a pretty good bargain for about twenty bucks per person. The captain is fairly informative, after your laps around Lake Union and Lake Washington, you have a pretty good idea of what all the strange looking equipment around the lake is. The location is excellent too, leaving you off in the vicinity of a number of South Lake Union/Westlake restaurants that are good for large groups.