Well I've finally made it to Rank 18. At about this point (really rank 16+) hours turn to days and days turn to weeks as you have to wait about that long to get enough money to do much. It seems like the XP increase isn't too much higher per level up, but I'll definitely need to get a Universe Dragon or start setting up my town for optimal gold farming if I want to get much further. Ideally, that means a ton of Aurora Peacocks or Flower Frillzards (or a few Universe Dragons if possible).
Courage though, Next Goal is rank 20, where I can finally find out what the Kung Fu Reseort does! (though I have a good idea of what it does. Every breeding game has some kind of "Fountain of Youth" building that makes your pets look like thier younger forms. I'll be making use of that cause some fo the Juvenile forms look SO much cuter than the adult forms.) After Rank 20, I'm gonna save up for that 15,000,000 expansion and get the White Tiger shrine. From there, we'll see what more there is to offer!