Pierce Transit has two trolley services that are offered only in the summer. One trolley runs in Gig Harbor (see trip directions for that adventure).
There is also a trolley running from the Tacoma Dome, down Pacific Avenue, then on to Ruston Way (along Commencement Bay) and then Pt. Defiance Park. The best of Tacoma! To see the specifics (time schedule, bus stops, etc… see: pierce summer trolley)
The Ruston Way trolley runs on Friday, Saturday, and Sunday ONLY.
Recently I caught the Intercity Transit Bus 605 from Martin Way Park and Ride on a Friday at 9:20 am. (Note on Saturday and Sunday, the 605 doesn’t run). I arrived in downtown Tacoma on Pacific (next to the State History Museum) a few minutes before 10. I walked two blocks past the Federal Courthouse and on to the Tacoma Art Museum. I highly recommend the “Immigrant Artists” exhibit that is on display this summer. 
The bus stop for the trolley (Route 15) is one block uptown from the Museum. It runs every half hour. I got off the bus at the Les Davis Pier, which is the second stop after leaving Old Town. From there I walked on the broad sidewalk/promenade. There are benches galore along this route… lots of strollers, dogs, and walkers! At Pt. Ruston, I turned onto the boardwalk, where a giant mosaic octopus embedded in the sidewalk greets you. I had a nice lunch at the Wild Fin restaurant at the far end of the complex. There are lots of places to eat in this upscale community.
By this point I already had walked 8,800 steps…it was getting hot, so I was ready to head back to town to catch the bus returning to Olympia. Last year I did continue the Route 15 bus (the stop is about a block up from Pt. Ruston) which winds through Pt. Defiance Park. A lovely route!
