One of Ulaanbaatar’s oldest hotels, the Zaluuchuud (Young People) has seen marginal upgrades since the Soviet era. Although bland and dated, it does have a quiet location in the University area. Not all the rooms are the same size, so you might try asking for an en suite standard, which includes a bedroom and a living room with TV. Room number 300 is a good choice.
Don’t expect much in the way of service, and steel yourself for the uncomfortable beds and the noise from the nearby karaoke bar.