This sounds quite interesting. I found some very good, free-to-use human models on the internet I could give you to use. Though, be warned... they have no clothes. This is so it can be fully customizable, with new clothes and such. .-. But, anyway, if you want the models, PM me. I could also be a modeler if you need one.
I also have a suggestion... Dragon taming/riding.
It'd be nice to have a pet dragon and be able to ride it. XD I also think the idea of pet stores and pets... like in the real world, but with mythological aspects, like dragons. Derp.