My only visit to the Isle of Man (so far) was in summer 2003. I went with my son - our first real holiday together - so it wasn't 100% railways and tramways, but it was close!
A particularly nice trip was from Ramsey down to Groudle on the fantastic electric railway. It's impossible to overhype this fantastic line which to me has it all. Scenery, interesting rolling stock, lots of interesting stops en route, serves a real transport purpose and has a fascinating route including private track and roadside running.
We went to Groudle to travel on the Groudle Glen Railway (story later!). The trip on the little line was dry, but whilst we were at Groudle MER station the heavens opened. As usual I moaned about it at the time, but looking at the pictures now the rain gives the pictures a real punchy quality.