Graden City Hotel is real nice but could take you 1-2hr to get to the city.
From Kennedy head for the Atlantic Beach Bridge. Atlantic Beach is on same sandbar as long Beach. If you're doing LB on the weekend have your car parked by 8-9am. During the week no problem parking. You may be able to rent bikes for the boardwalk at Wisconson & Beech St's bike store if you're lucky? There are surf shops around that'll rent belly boards etc.
what else?