Catalina Island, California
Size: 74 square miles
Population: 3,500 year-round residents
Located 22 miles from Long Beach, Catalina Island boasts a comfy temperature range, averaging from 75°F in summer to 65°F in winter. Head to Avalon, the island's only city, and check out the Mediterranean-influenced Casino (sorry—no gambling ). Big bands played the ornate ballroom in the 1940s; the Casino's theater now shows first-run films and is home to the Catalina Island Museum, which features an impressive display of local Native American artifacts and an exhibit on Hollywood's ties to the island (famous former resident: Marilyn Monroe). Outdoor activities include snorkeling and scuba diving in the underwater gardens at Lover's Cove—a protected marine preserve just minutes from the town center.
Getting there: Reach Avalon by helicopter in about 15 minutes, or take a one-hour boat ride from Long Beach or San Pedro. For transportation and lodging info call 310-510-1520 or go to catalinachamber.com.
Mackinac Island, Michigan
Size:3.8 square miles
Population: 535 year-round residents
About 300 miles from Detroit, Mackinac Island is a group-pleasing blend of a vibrant Victorian downtown and a state park. You can stroll, bike, or hire a horse-drawn taxi to tour the downtown area, which is famous for its fudge. Popular fudge stops include Kilwin's, Ryba's, and Murdick's, each of which has multiple locations, and Joann's. To burn calories, take a hike—over 80 percent of the island (1,800 acres) is state parkland. Mackinac Island State Park (906-847-3328) is open 365 days a year, without charge. Car-free visitors can explore scenic stretches of shoreline and Arch Rock, a popular 146-foot-high natural bridge.
Monhegan Island, Maine
Size: 1 square mile
Population: 65 year-round residents
As you ride the ferry to rugged Monhegan Island, you'll see the nearly-200-year-old Island Inn standing like a sentinel over the harbor. Rooms at the inn offer dramatic sunset views (207-596-0371), but leave your room for a bit to take on the isle's 17 miles of hiking trails. Families can walk in Cathedral Woods (a virgin spruce forest), stand at the precipice of towering 160-foot cliffs, and bird-watch at Lobster Cove. Fall is an excellent time for birding; the island is located directly in the Atlantic migration flyway, and Maine Audubon offers guided birding trips to view migrating thrushes and falcons, just two of the more than 100 species seen on the island (207-781-2330).
Getting there: Depart from New Harbor, Boothbay Harbor, or Port Clyde; the island is 10 miles from the mainland. For more information on accommodations go to monheganwelcome.com.