The best place a star can be Monday night is onstage accepting a gold statuette. But the next best place is at Irving Paul ''Swifty'' Lazar's 25th annual party, to be held as usual in the famed Spago restaurant. Around L.A., the literary agent's bash is often referred to as The Party. Swifty is more humble. ''It's just a party, nothing really special,'' he says. Among his regular pizza-munching guests: Paul Newman, Angie Dickinson, Jimmy Stewart, Bette Midler, Michael Caine, and Jack Nicholson. (A charity benefit for Central American refugees attracts younger, hipper stars, like Paula Abdul and Jodie Foster, and has been giving Swifty fair competition.) ''It's a hoot,'' says Newman, who so enjoys Swifty's shindig that in 1988 he departed in mid-festivities to present Cher with a Best Actress Oscar for Moonstruck then threaded his way back through heavy traffic to finish out the night. ''It's intimidating,'' says Dickinson, ''because so many important people just sort of sprout for this party who don't usually come out for social events.'' Years ago, Swifty's affair was, in Dickinson's words: ''a free-for-all.'' Not anymore. ''Now he sits everyone down during the show so we can watch the damn thing,'' she says.