Mice are way better pets than gerbils, much more friendly, and less hyper.

As for bedding, if you had carefresh before THAT IS WHY it stank! Carefresh smells like dead fish and amonia as soon as it gets peed on, it's just awful, TERRIBLE stuff!

Aspen will make all your non-stinky mice dreams come true.
And if that's not enough odor control, you can put PURE vanilla extract in their water bottle, and baking soda in the bottom (under the litter) of the tank in the corners.

And if THAT'S not enough, switch to pine, and continue with vanilla and baking soda.