Stan, all,
Got the LEDs from Town and Country and am quite pleased with them. For the 6 buildings in the picture below I reduced amperage from 3 amps to about 0.3 amps. Note, not all of the buildings take the Christmas tree plastic base (Menlo, Susquehanna, Police Station, Jahn's), the other use the bayonet style (bank, diner). Note the Menlo and Jahn's have extra stories and so they take about 20 and 14 bulbs respectively. In the picture below all of the 6 buildings have the LEDs except for the Menlo building so you can see the color difference. The transformer is about 15 or 16 volts. I didn't get a picture of the Menlo building yet since it took quite a lot of time to do.
Yes, the Christmas tree LEDs are a perfect fit for the MTH buildings. The one trick you have to remember is that since they are LEDs, position is important. They will light in one direction and not the other. Forgot about that fact until my handiwork reminded me of it and had to disassemble the buildings again. Note, a number of the MTH buildings just have 2 black wires, so you need to test to make sure which side is power and which ground, and to make sure MTH didn't switch the polarity on any of the wires at different stories of your building (ran into that one).
Overall I am quite please with these and will get some more from Town and Country. Also, ordered a 5 amp power supply I can set to 15 volts to power all my buildings now throughout the layout to make it easy.
Thanks for the suggestions.