Buckingham Palace Ballroom seats 170 for a lavish State Dinner that will occur for the Obamas on Tuesday.
The president and first lady usually stay at Winfield House while in England and will host a reception there during the state visit. It won't be a "knees up" affair like the party the Duke & Duchess of Cambridge had after their big do at Westminster Abbey. However, the newlyweds are expected to make an appearance on Tuesday to meet the Obamas, but Clarence House has yet to send out a formal message.
Every head of state gets a carriage ride after reviewing the troops. The head of state reviews the troops with Prince Phillip then rides down the mall in a regal procession with liveried footman to Buckingham Palace with the Queen in a gilt carriage. Lately the Queen has had more state events at one of her favorite palaces, Windsor Castle. However, the Obamas are staying in Belgian Suite on the ground floor of the Palace. Marine One will be nearby on the lawn. So...not sure if that particular carriage ride is on. (This carriage is carrying the Queen and President Zuma of South Africa last year.)
One of my favorite anecdotes happened on this side of pond during President Gerald Ford's one term. He wanted to dance with a more lively number and the President's Band jumped in with ... The Lady is A Tramp...She laughed out loud.