Wow thanks for all the responses! Seems like a bit of a controversial topic. Some dont do it at all and some wax everyyything. I think I will keep it simple and do it somewhere in between. I think I will reassemble the playfield before I wax. I will tape the star posts and apply my blitz wax I have on the areas that the ball travels on the playfield. I will not wax the plastic ramps/tunnels or the metal troughs.
Lastly, are you waxers avoiding mylar or applying wax on top? This is most notable for me on my Austin Powers.. the entire center of the playfield has a mylar protector on it.