I've done some really nice clearcoats using the DiamondClear product from KBS coatings. It comes in a can and you thin it out and roll it on your playfield, and it dries crystal clear and perfectly flat, rarely needing any polishing.
They've recently introduced an aerosol version that might be a bit easier to use for people. It's currently on sale for $17.95 per can. If it's as good as the roll-on version it might be better than the AutoMax product as it is decidedly less toxic.