Quebec City for 3 days

Then definitely find and eat poutine! Not a gourmet item but definitely part of the culture in Quebec. Berries of all sorts should be coming into season at the end of June - they are inexpensive there and plentiful. The upper part of the city has many wonderful restaurants to pick from - we usually wander and try whatever looks good and have never been disappointed.
Quebec City is hands-down the cleanest city I've ever visited. Both the air you breathe and the city itself is spotless and beautiful. We enjoyed walking the old fort to the east of the Victorian promenade. Walking the promenade and riding the funicular down to the lower part of the old city is fun. The lower old city is very touristy but still interesting to see.
One thing I wish we would have done was sail the St. Lawrence River - if you have the time it looks like it would be a wonderful, relaxing thing to do!

There's the fort to tour. Restaurants specializing in smoked meats. I would drive out into the countryside and find a market for homemade jams and maple syrup.

You must have breakfast croissants every day at Paillard on Rue St Jean. Best in the world I would say. Rue St Jean and Rue St Louis are your best bets for food within and just outside (west) of the gates. Don't miss the lower old town between the St Lawrence River and the upper old town. It's immediately below the Chateau Frontenac.

If you have an hour before your trip....you could watch the Anthony Bourdain episode of Parts Unknown about Quebec.
I really enjoyed it...and of course, he talks a lot about food!

Summary: ''Bourdain travels to remote areas within the province of Quebec where he samples local delicacies, explores ice fishing and beaver hunting and spends time with two of funniest and most brilliant chef/restauranteurs in Canada, Joe Beef's Dave McMillan and Fred Morin.''
And do try smoked meat and sugar pies! hmmm: http://lettucetalkaboutfood.blogspot.com/2010/03/15-things-you-must-eat-in-quebec.html
Hope you enjoy beautiful Quebec City!