There is but one full bath in our house. Which - depending on one's perspective - can be a good thing or a bad thing. Most of the time it's not a big deal...except when two girls and their guys are visiting, or when two of us are vying for the sink at the same time.
On the other hand, given the statistics that spouses speak to each other only 11 minutes a day, a single full bath per household might increase those numbers. Might increase the divorce rate too.