Florida
Florida is very popular holiday destination, spring time already starts in February. The obvious places to visit are Miami SoBe, with it's beautiful Art Deco district, Fort Lauderdale for gay night life. You can easily combine these with a rental car to Orlando for it's Disney theme parks and Key West.
If you have seen Florida already many times (like us) and visiting again for an all gay cruise for example, you can also easily combine it with Panama or Costa Rica. Only 2 hours flight time.
East Coast
The must see city is obviously New York City. Even if you have never been there, the city will look so familiar, due to all movies and television series recorded there.
Washington DC is also great for a sight seeing, and they got some exciting gay night life.
In Summer Province Town (PTown) is a very popular gay beach destinations. You can combine that with a day or 2 at Boston.
West Coast
California is the other part of USA with very good weather almost all year round. Gay heaven is of course San Francisco. Combine with Los Angeles / West Hollywood and a few days in the entertainment capital of the world Las Vegas. For the all gay life style go to Palm Springs.
Cities
Fort Lauderdale is close to Miami SoBe, and has a large gay scene. Each year the Atlantis Caribbean gay cruise departs here.
Key West is a beautiful island in the south of Florida, and popular as a gay destination. It makes a nice combination with Miami SoBe.
The LA gay scene is located in West Hollywood.
Miami South Beach is a beautiful place to visit. The island is all in art deco style. The weather is already good early in the year, and it has some nice gay places.