My humble Bonaire tips (been there twice).
1. don't pack you entire closet. Our first trip the wife and I brought way to much clothes. Last time I wore casual clothes down on the plane to also wear going out. You'll end up wearing shorts and t-shirts everywhere. (old t-shirts for diving, much to my wife's shagrin no one has ever stolen any of my Ozzy Osbourne shirts) There are lots of things to do on the island but by the second day you'll probably get into a routine of something like wake-eat-dive-eat-dive-eat-dive-pass out-rinse-repeat. Half way into your trip you'll be figuring out how you can get another dive in there.
2. Hit the supermarkets the first day and stock up on cold cuts, cheese, bread, etc... Go when the market is stocked b/c by the end of the week the shelves will be bare.
3. The guide book to shore diving Bonaire is good, but unless it was updated the morning of your dive, the diveshops are a better source. Don't be shy either, ask your neighbors where they went, and what they saw.
4. Beers are only 8 oz - buy twice as many cases as you usually do!
5. Don't be afraid to hit the same site mulitple times. if you feel you have to see everysite b/c you are worried about missing something then you will definitely miss something.