Somewhere fixed and somewhere sunny. And, the Doctor decided, somewhere they could have a good time. So, scratching off a number of natural disasters and wars, he picked out a particularly famous and particularly fixed large concert in New York.
He even had a tie-dyed tie that clashed beautifully with his suit.
"It's a bit muddy," he said as he attached an 'Out of Order' sign to the TARDIS. "But I think we're just in time to listen to Santana. Janis should be up in a bit, I might be able to introduce you two." A beat. "If she's met me yet, I can never remember, what with that whole mix-up with time..."
Still! No reason not to have a good time. He tinted his glasses and slipped them on, grinning madly at Jack as he did so. At least three days of fun, without the worry of something terrible happening, just so long as they stayed within the concert.