We've all worried what on earth the Democrats can do for money, now Averell Harriman's big bucks birthday is over. Catch up, please. There's the Senate Democratic Leadership Circle, chaired by Sen. Alan Cranston. For $15,000 a year, 164 deliciously rich members get to rub notions with the Democratic Mighty, at four big Sessions a year. Featured: Gloomy seminars on Reaganomics and Nouveau Defense Posture. The peppy bits: Fun soirees at Senators' houses. Sixty members and 35 senators bowled out for the latest, election week, chez John Glenn. Everyone was a scream. Teddy said of Glenn: "I can't understand why John would want to leave his fine rose garden for any other rose garden, can you?" George Mitchell of Maine told how he knew he'd done the right thing leaving a Federal Judgeship for the Senate when, his first week, he snoozed on an army cot by the Senate floor during a filibuster. In the next cot: John Warner. "I knew it wasn't too bad if John Warner'd give up a night with Liz Taylor to be with me." And Don Riegle said he wouldn't worry about any of them losing the next election, because they could all become comics in the Catskills. If he won't worry, Ear won't worry.