I had the same problem. The air wrench wouldn't even break it free. I got a breaker bar:
3/8 in. Drive 17 in. Breaker Bar

Then I soaked the bolt with PB Blaster (the best!) and got a 5 foot long pipe to use as a cheater. With enough soaking and using the added leverage of the pipe I got them free. With the cheater pipe over the breaker bar you can only move it a little, so it takes a lot of repositioning and patience, but you'll hear it creak and pop free. And make sure you are turning it the right way. On the driver's side, you'll be pulling up on the pipe and on the passenger side you'll be pushing down.

This was all 4 bolts on the front and two on the back.

When I reassembled, I put anti-seize compound on each bolt so that this won't happen again.
Permatex® Copper Metallic Paste Anti-Seize Lubricant, 16 oz Brush Top Can | Make More Happen at Staples®

 

This is a scary method I have used and it works... but be very careful if you try it.

Jack the wheel in question up much higher than you normally would with a floor jack. Put a cheater on your breaker bar and position it such that the end of the cheater bar touches the ground, make sure you are moving the cheater bar the right direction. Then SLOWLY lower the jack, the weight of the vehicle will apply pressure on the cheater bar to the ground and break the bolt free.

PB blaster is a good idea also. I'm not so sure about Anti seize on a caliper bolt though .. really you want a Caliper bolt to seize up a bit.

 

Mix ATF 50/50 with Acetone. Makes the best penetrant, really works!

 

Used a very powerful impact wrench and the bolt actually snapped off, but it came off! Thanks!

 

Sorry to hear that. Those things can be a real bear because the threads are so fine resulting in a lot of surface area. Are you going to be able to drill it out or did this ruin the caliper?

Also, the anti-seize is recommended for caliper bolts. It's not a lube; it has copper in it to make a barrier between the two metals to stop corrosion. It won't prevent the bolt from torqueing correctly and holding like it should. I use it on tire lugs as well.

 

You guys sound like you're talking about two different things from what the OP meant. I read caliper bolt in the post title but the OP described the caliper PIN being stuck in his first post. But then the convo went onward to talk about the caliper bolt instead of the caliper pin.

Caliper PIN and caliper BOLT are entirely different.