After playing something like 8 months (I don't know the exact number but I started maybe a month after release) I finally got a Dragonite through tons of egg grinding. That seems kind of long to me.
I've also literally seen maybe two Aerodactyls in gyms, and neither I nor my girlfriend have EVER seen or hatched one otherwise. I've not seen one in the event thus far either, but the event is basically my only hope.
The event has otherwise been good though (Slugma, Shuckle, Omanyte / Kabuto, Onix, Geodude, every one of which I needed), and I saw the first Electabuzz anywhere around in something like 7 months. I have a slight chance of completing my original pokedex besides the impossible other country ones (which I'm sad about).
Is it possible to hatch a Porygon? That's the massive blockade that's impossible for me to even grind, and it hurts because it has an evolution too. *edit* The internet suggests it's a 5k egg, though sadly I hatch tons of 5k's and haven't had any luck.