The easiest option is the Hanson Memorial Garage (entrance is off Brock Street, just north of Wellington). You can enter The Screening Room directly from the garage. Hourly rates are relatively inexpensive and after 6:00 pm you can park for the evening for $3.
Other neighbouring lots include the Robert Bruce Memorial Lot (upper lot entrance is off Montreal between Princess and Brock; lower lot off of Bagot between Princess and Brock) and the Chown Memorial Parking Lot (near the Grand Theatre, entrance off Brock just north of Montreal).
There is metered street parking available downtown on many of the streets. Luckily for us, street parking is free after 5:30 on Friday and Saturday and all day Sunday!