A couple of Mondale neighborhood parties last night lacked the cloud-nine ecstasy the Democrats feel is their right, but the Rothkopf soiree did substantial business in decaffeinated coffee and the Boyer-Taliaferro party ran heavily to orange juice. In general, bubbly went begging.

At both festivities, if that's the word, the rooms were full of Mondale neighbors (they live on Lowell Street) who vouched for the standard-bearer's interest in PTA and neighborhood affairs in general. One went so far as to say, "The Mondales are nice to other people's dogs."

None of which apparently impressed the American electorate. It may be the election was held in the wrong place.

"In a poll in the Netherlands," said Arnold de Vos of the Hague, who is attending an International Association of Political Consultants seminar in Washington, "Reagan won 17 percent of the vote. Ten percent were undecided, and Mondale won 73 percent."

Some felt the Democrats got geographically screwed up.

Alton and Cynthia Boyer and their house guest, Janet Taliaferro of Oklahoma City, presided over the orange juice crowd. A guest, Harry Walter of West Germany, president of the 100-member international group, said he would have voted for President Reagan if he were an American. (Stunned silence.)

He thought Reagan tapped the payoff reservoir of optimism, sound old values, zub, zub, zub, and he himself would have urged Mondale to appear less "negative." Four years from now, he speculated, the Democrats will be in the White House.

Cynthia Boyer, during a lull in which Reagan swept the Midwest, was pressured to take inquisitive guests to the basement where she makes felt from wool in her washing machine and turns it into expensive jackets. Joan Mondale wears one.

Arthur and Barbara Rothkopf held forth with the coffee, and the chief cheers exploded when a TV announcer said Washington gave Mondale three electoral votes, "and there it is twinkling on the map."

Hurrah! Hurrah! Somebody also speculated the Democrats might win the city council somewhere.

Asked what he found most encouraging about the evening, guest John McGrath thought a long time and decided the heavy turnout of voters here was fairly thrilling.

Hostess Boyer, back at the basement felt factory, said she never beats the hell out of the felt as many felt-makers do. But then nobody checked her out on this, at say, 1 a.m.