I took a few screenshots of using a Draenor Ogre model and an Elixir of Giant Growth to show off size comparisons.
I originally took some with the Draenor Ogre model roughly around Tauren height, which you can see here:
And the item I used to grow a bit was this:
And the results:
Comparing model size to a couple of NPC’s.
Comparing model size to a Tauren.
Comparing mount size to another mounted player nearby.
Comparing model size to other players at the auction house.
I actually grew in size a bit more than I thought I would. While I do like being big, I don’t know if I would see playable Ogres being roughly twice the size of other players. I do feel that the previous size, slightly around Tauren size, works just fine. Maybe slightly bigger than that would also work.
I do think finding the right size for playable Ogre models is important. They should be reasonably big, since it is a defining character trait of them. It does seems very workable to find a balance in size, too. I’ll likely see if there are any other items that grow your character different sizes and do screenshot comparisons with them to illustrate potential sizes for playable Ogres.
At any rate, whatever size they would be, I still hope to see Ogres on the Horde size of that character creation screen someday!
Dream big, Ogre fans! 
