I had a notion to do something with trams a couple of years ago, got as far as laying out most of the Llandudno and Colwyn Bay but foundered on the scenery. At various times I looked at other prototypes but never really got beyond the drawing board. Of course one of the biggest projects that hasn't (AFAIK) been done in Trainz is the Manx Electric Railway. Of course to do it justice would really require gauge specific prototype trams.
I have also thought about doing my own interpretation of Blackpool but, despite having achieved this in both MSTS and Railworks, haven't been able to motivate myself. Some of the fondest memories of my childhood were family holidays to Blackpool in the 1960s and early 1970's where for me at least, the trams were the high point of the trip. So although it is good to see the system thriving, IMHO the modernisation and introduction of the "Flexitys" has in some ways ruined the tramway, turning a unique transport system into just another light railway system.