The trip to Spencer Glacier/Lake involves a short train ride (depending on which train station you start from), a short bus ride down to the lake, and then a rafting trip partially around the lake, but mostly just floating down the river. Before actually getting onto the rafts, a nice little lunch was provided.
The lake area is a great site, especially having the glacier and many icebergs in the lake. The float trip, however, for Alaska standards, was very ordinary. The float was very very slow. It was scenic, but, again, considering other options in and around the area, it was a little boring.