the museum is good, its free also another bonus. its four floors high and you can spend hours and hours in it.
there is mary kings walk which is a guided tour underground but it may be a little scary for ds but i am sure if you google it you can judge for yourself.
having your photo taken next to the statue of greyfriers bobby.
vitoria restuarant is nice (There is about 3 in the city but the one on the bridge is family orientated. it is an italian and one of the best i have tasted. it is definitely worth eating there.
just generally exploring the royal mile and surrounding grassmarket are, take in the buildings, there are so many small alley ways to peep down and side streets to look at, perhaps let ds take pictures of the old buildings etc,
princess street is the more modern part with the high street shops etc
we love edinburgh and have been three times, we are going back in May