In past years, vacation for actor Hal Linden, TV's Capt. Barney Miller, usually has meant the end of June and two weeks at Christmas when his four children were out of school, and the family could be together. This season will be a little different because Linden is currently starring in the Kennedy Center's "Room Service" through June 25, and, anyway, the children are getting old enough to go on their own vacations.

During the winter holidays, the Lindens, whose home is in Los Angeles, like to balance a week in the tropical sun with a week at their ski condominium at Utah's Deer Valley. Once they rented a three-masted schooner complete with crew for a Virgin Islands cruise--"a wonderful week," says Linden--before flying off to the snow. Another time they sampled the beaches of Baja California in Mexico.

Adventure and the out-of-doors also characterize their summer trips, which are frequently to places where they have never before visited. Among Linden's favorite memories of family vacations:

* Whitewater rafting on the Colorado River in Utah: "We spent five or six days going from Green River to Lake Powell. We had a wonderful time."

* A safari in Kenya: "I have relatives in South Africa I had never seen. We spent a week with them and then went up through Rhodesia and on into Kenya for 10 days."

* A ramble through Scotland: "I rented a van, and we went first to Edinburgh. Then we decided, 'Let's go north.' We never had reservations. I just called ahead to inns and castles."

* A driving trip through Greece: "The kids were a little younger then. I rented a big van, and I plotted a kind of tour of my own. We went from Athens around the Peloponnesus, going from archeological site to beach to archeological site and back to the beach to keep the kids from getting bored with old buildings. It was quite a lovely trip."