the apple store has nice ones; clear, matte & privacy. They come in sets of 2 so you’re allowed 1 screw up. The trick to no bubbles is to slowly put it down on one end and gradually lay it down using your finger like a squeegee going back and forth smoothing it out as you lay it. If you just put the whole thing down in one shot, you’ll surely get bubbles.
InvisibleSHIELD ($14.95) is a really nice one. I bought the one they sell at the Apple store, but I really prefer the InvisibleSHIELD more. It has a silkier matte feel and applies very nicely. Here’s a video of the application process.
Depending on how paranoid you are, they also sell a full body version.