To check availibility on AA go to AA.com and as long as you have enough miles in your account you could play with different dates all day long. Just sign-in, go to reservations, click on Award tab, and you're ready to rock. Pick some imaginary dates and press continue and it will either comeback with flights available for the exact dates, or if not and a close date is available it will show you the options. Again, this will only work if you have enough miles for a Hawaii award ticket, which I belive is 35K for coach and 75K for F/B. You can't split awards with AA. They don't have one way option. It's either coach or F/B. Don't forget, once you ticket AA award ticket, you can't upgrade later, so make sure you could live with coach if that's the option you chose. There is a way around it, but it's costly, as it involves re-depositing miles and claiming a new award. Also any changes to a coach award ticket carries a price, while F/B ticket allows you to change dates without any penalties, as long as the new dates are available and the departure and arrival cities stay the same.
Good luck!