I was there (Rockhill) about a year ago, and really enjoyed it.
Their ride is really nice, and the scenery is beautiful.
We rode two normal cars on our visit (the open car, and their Johnstown car, at the time fresh from restoration.)
We also got a special chance to ride their bullet car, and see their large carbarn too.
My photos from the trip are here
http://picasaweb.google.com/StmTrolleyg ... leyMuseum#
One of the cool things is the way that the East Broad Top runs right onto the Rockhill property to wye the train - you're standing on the trolley platform, and then the steam train comes barreling through to turn around. Its really cool seeing period modes of transportation meet.
PTM might have a better carbarn, but I like the ride at Rockhill much better. Rockhills collection of cars is good sized, and almost all are under cover, although not all are on display. I really enjoyed my visit, and highly reccomend visiting.
I also went to Electric City (it was a PA roadtrip), and I really enjoyed the ride they had.
Their Philly center-enterance car is beautifull, and their line runs over some really nice scenery, especially through the Laurel Line tunnel (I think its a few thousand feet long. . .)
The center-enterance car is beautifully restored, and it rides like a magic carpet - you hear the wheels on the rail, but it rides likes its floating on air.
I thought the museum part of Electric City was pretty neat too. One of the main features they have is a Birney that they've cut apart, so you can actually walk inside it and see inside the various components of the car. (I know some people would say its a waste of a Birney, but I don't think it would do too well on their line. . . .)
My pictures of Electric City are here :
http://picasaweb.google.com/StmTrolleyg ... leyMuseum#
And here are my pictures of the ride on the Laurel Line
http://picasaweb.google.com/StmTrolleyguy/LaurelLine#