Level 22 now, and I've crossed paths with at least 10 random dragons so far. Killed 4 of them. The rest remained airborne, so I moved on. If you can't see them, listen for them. I would have missed quite a few if I didn;t know what to listen for.

Try Whiterun I hang around there a lot and I always see dragons.

i tend to go to the bars and stuff and ask them for work sometimes they have bounties for dragons....so i accept and go dragon hunting....i havent had 2 at a time or anything but they are def there.

I'm almost guaranteed to have one pounce on me whenever I exit a dungeon I just cleared and running low on Pots. It's happened to me more than a couple times. =/

I can't seem to go anywhere and not see one.