For more options, checkout the Ford House Retreat and the Shambhala Guesthouse. They are located 30 kilometres and 30 kilometres respectively from the main center. If these don't meet your needs, you can try the Nelsons of Bridgetown or the Pamela's Retreat.
The close by cities of Nannup and Collie are definitely worth seeing. Nannup is 30 kilometres to the southwest of Mullalyup, while Collie is 50 kilometres to the northeast. Accommodations in Nannup include The Black Cockatoo Nannup and Holberry House. The Collie Ridge Motel and Banksia Motel Collie are some of the better ones in Collie.
Hotels in Mullalyup start at AU$80 per night. Prices and availability subject to change. Additional terms may apply.