I use Cling Vinyl, a clear contact vinyl. It is pretty awesome stuff, because you can peal it up and replace it when it gets dirty or wrinkles. I like to put strips on the shooter, in lanes, and hi wear spots. You can get it in sheets or rolls.
http://www.amazon.com/Grafix-9-Inch---12-Inch-Cling-6-Pack/dp/B002J6CO9I/ref=sr_1_1
I'd also like to hear what other Mylar alternatives people are using.