Contests and Prizes, Oh My- what do YOU think?

We're getting ready to launch something BIG with International Heat- at the start of October in fact- shhhh, it's a secret still. And I'm playing with prizes.

What do you think? which do you like better?

1. Prize packages where there are books set out already so you know what you're winning

or

2. A chance to get winner's choice of books?

What would you consider a GRAND prize? Help me out here, and give me a few ideas. I've got some nice things falling into place, but I'd love to know what...