On a day trip from Seattle I visited the Tacoma streetcar, which like the Seattle Link Light Rail is operated by SoundTransit (while the Seattle streetcar is run by King County Metro, the local bus company). As described in the Seattle blog, if you want to use only rail to go to Tacoma on a day trip, you need to get up early for one of the two southbound Sounder trains (I'm not sure whether you could also take Amtrak's Coast Starlight, which leaves Seattle at 9.45 am, or a Cascades train at 11.25, you probably could, but it has occurred to me just now). Anyway, otherwise there are frequent buses, at least hourly during off-peak, and then there are two trains back at 4.25 pm and 5 pm.
The Tacoma streetcar is among the smallest tram systems in the world. Its main function is to link the transportation hub at Tacoma Dome (buses, parking lot, Amtrak station and Sounder station) to the city centre – and best of all, the ride is free. The first section to just before Union Station is single-track, while the remaining section, except the terminus at Theater District, is double-track. There is another major bus station, but this is located exactly between the last two stops, Commerce Street and Theater District, so transferring passengers always have to cross one street. The stops are pleasant with all necessary information and shelters, but no next-train indicators. The trams are almost identical to those in Seattle, although here they carry the Skoda label as the manufacturer. They run every 12 minutes, a headway that results from the overall travel time of about 10 minutes and the single-track section on one end. They two trams in service mostly meet at Union Station (a name that refers to the well-preserved old railway station building nearby which now accommodates a courthouse). Tacoma's major tourist attraction, the Museum of Glass, is located next to it. Being free, the trams get quite busy, although the city (or town?) as such seemed rather deserted.