What to expect: The Key Largo Grande Resort attracts families seeking the pleasures of water sports, swimming, and nature walks. The lobby has tall windows and a central elevator shaft constructed of white coral. Behind the hotel, a quarter-mile boardwalk trail winds through 12 acres of "tropical hardwood hammock," which contains many rare and endangered species and are named after an Indian word for "shady place."

Amenity highlights: Surrounded by dense, blossom-festooned foliage, Key Largo Grande Resort & Beach Club offers a small, secluded, private white-sand beach edged by coral formations. Lounge chairs can be set in the sun, under tall shade trees, or in the shallow Gulf water. Two swimming pools, one for adults only, are separated by rocks and cascading waterfalls. A spa tub is surrounded by a high wall and flowering garden near the adult pool.

Insider tip: Widely separated on the resort's long, L-shaped pier, two benches provide ideal spots for privately observing sunsets and contemplating the Gulf's serene water in moonlight.

What to expect: Mariner's Resort Villas & Marina welcomes guests by land and by sea – boaters can dock at the resort's 43-slip marina, which is tended by a full-time harbormaster and marina staff. The villas and townhomes of the resort feature views of the marina, grounds, and ocean, and are surrounded by lush tropical landscaping.

Amenity highlights: Visitors can take a dip in one of the resort's two swimming pools or soak in the coral grotto spa tub. For more adventuresome water sports, guests can sign up for scuba diving or snorkeling at the resort's on-site dive shop. The resort also offers two tennis courts, an on-site restaurant and tiki bar, and a fitness center equipped with cardio and strength-training machines and free weights.

Insider tip: A 200-foot pier leads out to an observation deck over the Atlantic Ocean. It's an ideal spot to catch the sunrise or enjoy a quiet moment.

What to expect: Lightly illuminated by neon at night and basking in sun and ocean breezes during the day, the 17-acre resort attracts vacationing families seeking island ambience, lots of water sports, and kid-friendly fun. Noisier activities are concentrated on one end of the resort, leaving the other end quiet for adults to stroll along the marina's Gulf-side promenades and relax in shady cabanas.

Amenity highlights: The oversized swimming pool stays open late. A fountain and six-person spa tub are adjacent to the pool and surrounded by lounge chairs and palm trees. The Marriott's private, 125-foot white-sand beach slopes gently into calm Gulf water. Thatched cabanas offer tranquil rest and sunset views along waterfront promenades fronting the marina. An open-air health spa offers massage and body/facial treatments amid gauzy curtains ruffled by bay breezes.

Insider tip: Three miles offshore, in international waters, a casino yacht anchors daily from afternoon until late evening. The hotel provides a complimentary water shuttle to and from the vessel. Onboard, guests enjoy live entertainment, complimentary hors d'oeuvres, card and dice games, roulette, and slot machines.