Shavings are my last choice for bedding. Hardwood pellets (sold as fuel for wood pellet stoves) work well in terms of keeping smell down; pine pellets (sold at feed store as horse stall bedding) work even better. I know, you "can't" keep rodents on pine -- but the only studies to this effect that I've seen have tested pine shavings, not pine pellets. My mice (~10 colonies) do well on the pine pellets. The pine pellets turn to powder easily, though, so I mix pine and hardwood 50/50. Need to clean every 10 days or so with 1.4 breeders and young in a 10g tank.

FWIW, I've tried baking soda and found no reduction in smell.