Like Pete said - top.
There is so much room in the 820 up top, that both the rad + fans can go under the top compartment (not in it), and there'll still be a couple of inches room from the fans to motherboard. You could even do push/pull and it wouldn't reach the motherboard, plus you'd still have the top compartment free. That's how much room there is.
Front 200mm: intake (included)
Side 200mm: intake (included)
HDD swivel 120/140mm: "intake" (if you add an extra fan there)
Rear 140mm: exhaust (included)
Top Rad + fans: exhaust
If you're wondering what to do with the top 200mm fan, I'd keep it as a spare. There is actually room for it in the bottom. I fitted it there (using some sponge bits to wedge it snugly between the sides as there are no screws for 200mm on the bottom) just to make use of it. But it doesn't push much air because the vents are for 120/140mm, and the hub on the 200mm is bigger than on 120/140 fans. I could take it out for all the difference it makes.