The beaches to avoid include Avalon Beach and Orange Doheny State Beach in California. Lake Jeorse Park Beach in Indiana, Beachwood Beach in New Jersey, Ontario Beach in New York, Ashtabula Lakeshore Park in Ohio and Milwaukee South Shore Beach in Wisconsin.
If they want to go to one of the better beaches, Duluth, Minnesota's 13th Street South Beach is rated among the best beaches according to the report. I've been there and can recommend it. Same-sex marriage becomes legal in Minnesota on August 1, so maybe the justices can plan their trips to Duluth based on how they voted in the DOMA case.