I've been filling in the grades under my elevated track sections, adding some cork "ballast filler", and installing LED lighting in some passenger cars. 
Here's a shot of the Bay Head section, with some of the cork showing. The idea for cork "filler" came from Dennis Brennan's book, "Realistic Modeling for Toy Trains". It's an extra step, but by volume, the 1/8" cork I'm using is half the price of the ballast I'm going to use on top of it.
For filling in the open area under my grades, I'm using plaster wrap, which will be covered with tinted plaster as the scenic base.
Here I've started to apply tinted plaster, just smearing it on by hand. By the way, don't ever use low-adhesion masking tape to protect the tracks. The adhesive sticks to the tracks and is a pain to get off. 
Every now and then I switch to something else, like installing LED lighting in my passenger cars. These shots show installation in 60' (3 LEDs) and 70' (5 LEDs) MTH cars. I'm using warm white LEDs from Christmas tree strings. The 12V power supply board I use is the 3 LED light strip from Electronic Goldmine. I remove the board mounted limiting resistor and tap into the 12V at the filter capacitors, with external limiting resistors added.
Topside 70' board.
bottom
Back to plastering!
Gary F.
