Go on a boat ride
Do a once in a life time thing (something you'll never forget) think big and go wild!
Hire a look-alike celebrity for the day
Have a vintage tea party
Host a barn dance. They're so much fun and will have everyone up dancing and laughing their heads off.
Go on a Superbreak. You can choose an attraction to go to and get a lovely nights accommodation to go with it
Ticket to ladies day at Ascot
Put up a 60's themed party
Treat yourself to a theatre package
Go to the London Zoo