The best whale- watching on the East Coast leaves from Provincetown on Cape Cod, where some boats sight humpbacks and finbacks, claiming a 99% success rate from April to November.
On the West Coast, you can see Pacific gray whales during their spring and fall migrations from Point Reyes National Seashore north of San Francisco; Depoe Bay and other points on the Oregon coast; and the San Juan Islands near Seattle, which also have orcas.
The port of Sitka in southeastern Alaska, Kenai Fjords National Park, and nearby Seward are great spots to watch humpbacks feeding in summer -- plus a profusion of seals, otters, and other marine mammals.
For many humpbacks, the fall migration takes them south to sunny Hawaii, where they frolic in the warm waters from December to May. They are best seen here from Maui's west coast.
For wildlife-watching, you can see moose in Rocky Mountain National Park in Colorado, maybe a bear in the Great Smoky Mountains, or alligators and other critters in Florida's Everglades. But the best places to spot a variety of animals are undoubtedly the national parks out west and in Alaska. Without question, Yellowstone offers some of the top opportunities, with an abundance of elk and bison. Some of them will walk right up to your car. Glacier has this and more -- mountain elk and the occasional grizzly bear. Alaska's Denali national park offers visitors a great chance to see grizzlies and other types of bears.