Bards do not sleep.
Stewards and Housecarls have the single beds on the second floor for their use, but only if certain conditions are met. If you do not build the bedroom wing with beds for kids, then if you adopt any kids, the single beds on the second floor become the kids beds. At that point the steward and housecarl will no longer have a place to sleep. Even if you make the bedroom wing later those beds will still not be available to to the steward and housecarl. So if you are going to have any kids at the place, build the bedroom wing before adopting.
Another gotcha is that if you build both the double bed on the second floor and the double bed in the bedroom wing, then the steward will glitch out and stand next to the double bed on the second floor from 12 AM to 6 AM rather than sleeping in his/her own bed.