FOR A DIFFERENT kind of vacation -- one loaded with delightful fringe benefits -- you can't beat a short stint on the campus of some college or university.

I chose the "winterim" -- the period between the autumn and spring semesters -- to enroll for a three-week course at the College of Boca Raton in sunny Florida. From Jan. 7 to Jan. 25, I earned three hours of college credit in American Government. While wintry gusts swept Washington, I was basking in South Florida's 75-degree temperatures.

The class was a happy one, ably conducted by Dr. John Pickering. Reexamining the work of the Founding Fathers in this election year lent currency and pertinence to what had been for me, at least, a topic both dry and remote. Our class, which contained 10 students, met from 8:30 to 11 a.m., five days a week. Including weekends, I was in residence on campus for 19 days.

I was assigned a single dormitory room in the faculty wing. It contained a comfortable bed, chest of drawers, closet, desk and chair. Showers and toilets were down the hall. Meals were served in the college cafeteria and the food was wholesome and plentiful. Some found the regimen spartan; I found it pleasant. And the fringe benefits were spectacular.

As a "student," I had free access to the college tennis court and swimming pool. A nearby municipal golf course offered a discount membership for a month's pay for $30. I also rated a student discount card which admitted me to half a dozen movie houses in he area for half price -- not a bad deal for a "senior citizen." A daily bus took students to the beach in early afternoon and returned before 6 p.m.

Most of all I enjoyed the easy, casual campus existence, the large library, and the relaxation which comes from reducing all of one's problems -- for three weeks at least -- to the academic.

It was a mixed bag in residence at the College of Boca Raton. In addition to students of assorted ages who dropped in from West Virginia, Illinois, Missouri and New Jersey, the college had rented its facilities to a baseball school and to the American Institute of Real Estate Appraisers. aThe baseball players come and go from mid-December through August; the real estate men were there for three weeks and provided their own special instruction for appraisers in the college's classrooms. the College of Boca Raton highly. The 123-acre campus, dotted with lakes and plam trees, affords a restful background for strolling and meditation.

My days quickly settled into a pattern: Rise at 7, breakfast in the cafeteria at 7:30; walk to class, about 300 yards; in class from 8:30 to 11; lunch from 11:30 to 1; siesta until 2; tennis or golf, swimming or beachcombing in the afternoons; dinner 5:30 to 6:30. Evenings were divided between study in the library, drinking beer or wine in the school's well-run rathskeller or a visit to one of the plentiful night spots or movies along the Florida "gold coast."

The cost of all this was a distinct bargain in these times of energy crunch and galloping inflation. The roundtrip air fare, Washington-Miami, was $148. The bus from the airport to Boca Raton was $11 each way. The all-inclusive fee for room, board and tuition at the college was $385. For less than $600, I had a 19-day vacation in the sun -- with a little mental stimulation thrown in for good measure.

As the oldest (by a good 30 years) "student" in my class, I got a fresh look at the current youthful point of view. I found it rational and subdued -- not in the least anti-establishment. An air of sobriety, determination and hard work prmeated the group. Most of these young people were using the "wintrim" to earn credits and graduate earlier.

Economically, the "winterim" makes good sense for the college, too. Instead of shutting down for three weeks with the attendant loss fo revenue, it was running full blast with 500 persons in residence,close to the normal student enrollment for the academic year.

Three other colleges in Florida offered "winterim" course this year: Eckerd College of St. Petersburg; Rollins at Winter Park; and Stetson University at Deland. Boca Raton also offers a spring course, which begins May 19 for three weeks.

The largest student representation from a single school came from West Virginia Wesleyan College. Some 30 students and six faculty persons were at Boca Raton from Wesleyan. It was the third consecutive winter appearance at Boca Raton for the West Virginians.

It's impractical to compile a list of the schools which offer "wintrim" and spring course of the three-week variety because plans, courses and programs are often subject to quick changes. For those who want to return to school for brief periods, either as vacations or for additional college credit, it is best to choose your area and then inquire among the schools in the neighborhood. One of America's college campuses may well offer a unique and informative vacation.