My family and I have been coming to Pantheon for years; very rarely do they disappoint. The atmosphere is lively, the waiters are courteous and friendly and there's always flaming cheese (cheese saganaki) and shouts of "opa!" in the background. Plus, if it's your birthday, the waiters will bring out a generous slice of honey cake at the end (with a candle, of course) and belt out a loud, unabashed version of "happy birthday"!
Although the souvlaki are excellent (I've had the pork and chicken; both moist), my usual order is the grilled calamari dinner ($19.95). It comes with 3 large pieces of calamari, 2 tentacle "bunches", potatoes, carrots and broccoli. The portion sizes are sooooooo generous - I guarantee that you won't leave hungry. The calamari was super tender and seasoned very well; a squirt of lemon on top just seals the deal.
At the end of every meal, they will give your table a complimentary slice of their honey cake. Even though I'm full after the calamari, it's like I have a separate stomach for the cake (funny, how that works).
TLDR: one of, if not, the best family style Greek restaurants on the Danforth.