In Washington, they will inhabit a 115-year-old Victorian with 33 rooms on a heavily guarded circular lot, next to the British Embassy.

The Bidens and their aides declined to discuss their plans or the question of whether Dr. Biden would find a new job in Washington. But friends and colleagues said that in all the decades Mr. Biden worked in Washington, he never had much of a social life there. He rarely stuck around for an evening fund-raiser or a cocktail party. He was not a regular at typical lawmaker haunts like the Capital Grille or Charlie Palmer, instead inviting people to the Senate dining room if he happened to be in town for dinner.

“I think he was far more interested in his children than the social whirl,” said Senator Patrick J. Leahy, a longtime Biden friend. “I have to kid him a little bit, because he’s no longer going to be asking, ‘Are we going to finish this vote by 7:45?’ so he can make this mad dash to the train.”

Not that Mr. Biden will suddenly become a fixture at Washington dinner parties, predicted Mr. Leahy, who in his 34 years in the Senate has seen a few new administrations come to town. “Everybody loves to have the vice president over for dinner, and he’ll have 100 invitations piling up,” Mr. Leahy said. “But I think he can be very valuable to President Obama up on the Hill. That will be the most important place to be.”

Sally Quinn, the journalist and author, said that like the Obamas, who have spent little time in Washington, the Bidens will be social newcomers.

“I’ve never seen Joe Biden at a party in Washington,” Ms. Quinn said. “Both of those couples are going to be fresh faces, even though they’ve both been in the Senate and Biden’s been here for a hundred years. It’ll be very interesting to have them around.”