As most Americans ponder their Thanskgiving turkeys, Democratic Party officials are migrating to this tropical island to lick their wounds from last week's landslide loss at the hands of President Reagan and ponder their future.

If sun and sand were a political philosophy, the Democrats might have stumbled onto the key to success. But nothing comes easy these days for them. A hurricane hit the island last week, somewhat like the one that hit presidential nominee Walter F. Mondale, and things aren't quite back to normal.

Mondale was at the airport today, looking tanned and relaxed after a week's vacation on nearby St. John's island. He was heading back to Washington, passing up a chance to participate in the weekend discussions.

This meeting of the Association of State Democratic Chairs once was seen by some optimists as a relaxing victory celebration. But after last week's presidential rout, the weekend retreat is likely to be the opening round of what one official called "the blame game," a battleground for assessing what went wrong and what the party must do to recapture the White House in 1988.

Southern party chairmen, who have begun to air their grievances since Mondale's defeat, are a powerful and vocal force in the state chairs' organization. Democrats generally, and southerners in particular, are wrestling with how to appeal to moderate and conservative white voters who abandoned the party for Reagan, while satisfying demands among blacks -- the party's most loyal constituency -- for a greater voice within the party.

This could come to a head during a discussion Saturday on the Fairness Commission, a party unit being created to respond to complaints from Jesse L. Jackson that the delegate-selection rules discriminated against his presidential candidacy.

There are persistent rumors that Jackson will attend part of the meeting this weekend.

The chief order of business, however, is expected to be politicking for a new party chairman to succeed Charles T. Manatt, whose term expires in January.

There are all sorts of announced and unannounced candidates, but the first question before the party is whether to choose an elected official who could serve as a national spokesman for it or a more nuts-and-bolts party activist who could concentrate on more traditional party-building activities of the kind begun by Manatt.

Some party leaders say a combination of the two might be the best solution. Republicans have such a combination with Nevada Sen. Paul Laxalt as general chairman and Frank J. Fahrenkopf Jr. as chairman of the Republican National Committee.

Democratic governors, led by Arizona's Bruce Babbitt, are pushing for an elected official as the new party leader, and at least two departing officeholders, Massachusetts Sen. Paul E. Tsongas and Utah Gov. Scott M. Matheson, have indicated that they are interested.

Another elected official being considered is Rep. Tony Coelho of California, who chairs the Democratic Congressional Campaign Committee and who has won praise among party leaders for limiting Democratic losses in the House last week to 14 seats. Coelho favors a change in the party charter that would allow creation of a general chairmanship in addition to a day-to-day chairman.