During our 2010 Fest in the Pacific Northwest, we rode the Portland Vintage Trolley around the downtown loop in that city. We only had time to do it because the Willamette Shore Trolley (a tourist run between South Portland and Lake Oswego) was not running (and STILL isn't). When we rode it, the operator's commentary told us that 2010 might be its last year since there was a move to discontinue it.
Well, good and bad news. It's still in operation, but instead of every Sunday in the summer, it is now only selected Sundays -- mostly holiday weekends and every Sunday in December.
More here, including the new schedule which was just published June 17, 2012.