WHETHER MR. REAGAN runs or not, Democrats across the land obviously have their sights set on Washington in 1984. They should know that the reverse is true: Washington has its sights set on the Democrats. This city, along with its two neighboring governors of compatible partisan affiliation, is eager, ready and perfect for the party's national convention. What better site is there than the president's back yard to call the roll and coalesce for the big challenge?

All the ingredients for a good, big-league time are in place here, with easy access to and from a brand- new, fully equipped convention center; Eastern Daylight Time for the primest of TV exposure; the security of a strong, thoroughly experienced and highly regarded police department; ample accommodations; and more free and interesting goings-on for families than any other city we can think of. And if, as they say, the clerk will call the roll, it would show that about 62 percent of the delegates are within a 600-mile radius of Washington.

More and more visitors are discovering something else about Washington--that beyond the formidable and fascinating monuments and federal buildings is a city of local people with their own hometown hospitality and lore.

That's the platform, and it's there for the adoption. Washington's a natural--so let's have the party!