Worth noting is that the South Lake Union Trolley was built by Paul Allan, of Microsoft fame, to serve his various buildings & properties in the area. This system, as I recall, was NOT built with public tax money, although City of Seattle did street improvements concurrent with the project. This system does not, and probably will not, connect to Sound Link, the Seattle to SeaTac light rail project. The SLUT project, BTW, wiped out the last remnants of Northern Pacific's street trackage in the area.
Regarding light rail plans to the 'Eastside', ( Bellevue / Redmond / Kirkland, WA. ), the NIMBY's are out in force. A " citizens group " has been fighting plans to route the tracks in the reversible HOV lanes of the Interstate 90 floating bridge across Lake Washington, despite the obvious mass transit advantages. Another group, led by Bellevue developer Kemper Freeman, doesn't want ANY light rail in downtown Bellevue, while yet another group ( homeowners ) doesn't want the tracks routed over the ex - BN Woodinville Sub, a natural choice for the line.
Meanwhile, the Link expansion from downtown Seattle to Northgate is spending BILLIONS & BILLIONS of tax dollars to dig a TUNNEL hundreds of feet deep & several miles long under the Montlake Cut of Lake Washington AND the University of Washington campus, while the obvious route on the lower deck ( reversible express lanes ) of the Interstate 5 bridge over Lake Union was ignored. I'm waiting for the tunnel crew to break through the Montlake Cut & drain Lake Washington into it, like what happened years ago in a coal mine under the Susquehanna River near Wilkes Barre, PA.