pinnacle offers 10% bonus on initial sign-up, which is less than a lot of really great books (like jamaica, already mentioned, and olympic, bowmans, etc. etc.)
BUT........pinnacle has the lowest juice on the net. it will save you a helluva lot more money in the long-run than the the cash you'll make on that extra 10% bonus you might take with another book.
so skip the 20% bonuses, and go with pinnacle's 10% bonus and play at the best book in the world.