Hi highdiveone,

The Dalmahoy public areas and golf course look beautiful( we were there for a one day conference)
It is in the countryside past the airport so you will need a car to go into edinburgh (probably very limited bus service past the hotel although i think there is a courtesy bus service to the airport from ehere you could get a bus into Edinburgh city centre.

As you are coming in September the festival and tattoo will be over so the city will be quieter.

A few things to do in Edinburgh
Visit the Castle
Walk down the Royal Mile (stopping in at a few pubs down the way)
Walk along Princes Street and the Gardens
Walk up Scotts Monument in Princes Street for great views
Vist the National Art Gallery of Scotland and the National Museum
If you like walking and it is a fine day walk up Arthurs Seat (800 foot relatively easy climb)

Outside of Edinburgh for day trips you could visit Glasgow (50 minutes by train)
St Andrews is not too far away by car over the Forth Road Bridge.

I would bring layers of clothing to wear and something waterproof as we have had a lot of rain recently (unlike Scottsdale where I visited in June)

Drop me an email if you want any more advice.

Have a great time when you come to Edinburgh

Regards
TBS