Originally Posted by
SalishSea
In Paris: You could take one of the one hour boat cruises along the Seine. You'd get some great photo ops, a little history, and some fresh air.
After that you could enjoy a leisurely lunch in a cafe.
+1 on the boat trip. I seem to remember the boat has a stop quite near Notre Dame - you could get off and visit Notre Dame and take a stroll round the Ile de la Cite.