I want to second the idea of steam cleaners on carpets. It is just amazing how much dirt they suck out of the carpet that vacuum cleaners don't bring up. We take off our shoes at the door, so we're walking around in bare feet (or socked feet) all day. Even so, the carpets somehow get very grimy. It's just amazing. So it's important to me to steam clean them fairly regularly.
All our floors are carpeted except our kitchen and bathrooms.