Located in Morrisburg, about 30 minutes west of Cornwall along the St. Lawrence River, the Upper Canada Playhouse offers some fantastic comedies throughout the summer. Be sure to pick up a schedule and drive down, especially if you're planning to be in the area to visit Upper Canada Village just east of Morrisburg.
Dress Code: Nothing fancy, but some people dress up a bit.
The Glengarrian often has live music on Friday and Saturday nights. Great Celtic acts, usually local, make stopping in for a pint and a two-step a must. Be sure to get there fairly early - the pub is small and the area loves its Scottish/Irish music.
This is not exactly a theater. More like an outdoor amphitheater. It is located in Lamoureux Park. Often they hold outdoor concerts here with local bands or children playing. You can easily find a pub with live music, open late at night. Many of them serve food and don't charge a fee to enter their establishment. This outdoor theatre is right besides the civic center in old Cornwall.
Dress Code: Dress for windy weather outside. Especially in the evening.