IMO the smoking sections are pretty clearly marked on the maps...(little smoking symbol)...being a smoker - I have my favorite ones - there are more available - but these are all I can remember. (maybe other dis'ers here can help you create a full list...)
MK
If you are facing Pirates of the Carribean - to the left around the corner
Facing the Dole whip counter - to the right (actually a nice one - in the shade w/ chairs/tables)
Near the McDonald's cart that sells fries - however, the birds are HORRIBLE here, so I reccommend finding a different one!

Near the tomorrow land speedway - if you are looking at it - to the right and down a small hill. (you can watch all the kids attempt to drive - too funny!)
facing space mountain - take a right and head towards the rest rooms - keep walking and it's just past them
I know there's one near the HM too...can't think of it though
EPCOT
In front of Mission Space (between that and Test Track) there is a little tucked away place - walk down the stairs to it)
Near Ellen's energy adventure - I remember sitting down with coffee watching the kids in the fountain, so I guess there's one around there
Outside of The Land between The living Seas
Almost every other country has one - some tucked away, some right on the 'main' walking path.
MGM
right when you walk in, there are bathrooms off to the right - also a smoking section
Near the exit of Tower of Terror - where the gift shop is, back in there in the corner (nice and shady too)
Facing the Great Movie ride - walk to your left...a bunch of tables/umbrellas - also a smoking section
outside of Sci-Fi Cafe - facing the restaurant, turn around and walk straight.
Where that big dinosaur is in the middle of the lake (it's an ice cream stand? heheh) Face that, turn to your left, walk a few feet - right there.
AK
These are probably the hardest to find...
In Harambe - there is the Dawa bar, behind that is a smoking section
walking to Asia from Africa - there will be a hidden path on the left...very secluded smoking section
I believe there is one outside of Restaurantasauraus (or whatever that place is called that serves McDonald's)
These are all I can remember right now - I'm sure others will be able to direct you more exactly...but really - when it doubt - just ask a CM!
