A nice pub for lunch is one thing but finding a spa sounds a step too far.
Over the years I have found that my wife just doesn't mix much with my flying. If I tried to do what you want, there is rather a risk of succumbing to "get there itis" or "get home itis." My wife comes when she is wiling to enjoy the day and go flying for flyings sake, not because I have made some promise to her I may not be able to fulfil.