I had hamsters and guinea pigs growing up. I also worked at a pet store in college where my job was to care for all the small animals. I recommend a guinea pig over a hamster for sure. They are much more social and fun. I have never been bitten by a guinea pig, but I've been bitten numerous times by hamsters. The dwarf hamsters were the worse!!
We have a guinea pig currently. I use a product from Petsmart called Carefresh Natural pet bedding. It is really absorbent and the cage never smells. It is much better than the wood chip shavings I used to use.