The way I cut down on the smell of the rats is just to clean regularly. Maybe use one of those scented oil plug in things(I use the green tea and mandarin one, it's awesome).

Use aspen(when pine is wet it STINKS) and mix it with yesterdays news and provide litterboxes. You can use a bit of baking soda mixed in the bedding too. Change out their hammocks every few days as well as wipe down their shelves with a very mild bleach solution(or the Clorox Anywhere spray).

They are girls, so putting vanilla in their water isn't going to help. You can bathe them once a week or every other week if you want. Baby shampoo or kitten shampoo (not anything with flea stuff in it) would be appropriate.

Also, making a spray with a bit of mint oil(very weak) in it, and spritzing everything lightly with that helps a good bit, and they like it.