If you want a mirror finish, sanding and buffing is the way. I go 600 grit on stuff that's scratched. Then to black rouge on a cutting wheel, then red rouge on a soft wheel. The key is to get it hot. it's very forgiving until you slip and hit the buffer mandrel or let it get away from you... only problem is, once you do one piece, the window trim will look like crap and you'll end up doing every piece on the car!
Bee, have you ever dealt with getting it too hot? It will start to discolor and turn blue. Then you have to polish that off. This has happened to me, especially on small, thinner pieces. I avoid that by keeping the piece moving and never lingering on the same spot too long.
Perfect observation about the work escalating.