A lot of people forget about Puerto Rico - it's part of U.S. so you don't need a passport, you use U.S. dollars, there's a lot of English spoken. If you have some Spanish at your command, it's appreciated.
There's a rainforest there (El Yunque, the only rainforest on U.S. territory), old San Juan on the north coast, (with fort and museums and charming streets), beaches, Phosphorescent Bay on the south coast, rugged terrain on the west coast, the famous Ponce fire station and markets, and much more. You fly to San Juan, you can rent a car and travel around the island in 2-3 days if you want to stay in a few places, then wind up back in San Juan to fly out, saying a few days there as well. Or just go to one place and stay put, taking day trips only.
Speaking from personal experience, Cape Cod and New England are great. Maine coast is rocky and water is cold, Cape Cod has ocean, sound and bay sides with big/medium/no surf. Newport RI has mansions and jazz festival and Cliff Walk. Everyone has seafood. If you like the fall foliage season, I know a great inn in NH - my husband and I have been several times. Romantic, nice staff, phenomenal food. We've also been to a great resort on Lake Champlain in VT - cute cottages, fab food, many activities including golf and boating and relaxing.
If you like excitement, do NYC with theater and museums and night life and many ethnic neighborhoods/restaurants, plus plenty of history.
CA - wine country, Napa, San Francisco, rent a car (I suggest convertible - we did!) and do the coast highway, go to Carmel and Hearst mansion and Monterrey.
Just random thoughts with no idea of what you two like to do!