Camera Obscura. Definitely. It's SO awesome, and we didn't go last time, I don't think.
What sort of things do you guys like? The Dean Gallery is great, even if just for the gigantic metal statue of Vulcan. The Museum of Childhood is fun, as are the other museums. Ooh! I should see if there's an event at Lauriston Castle again! And it's just round the corner (sort of) from Cramond, which has beaches.