My husband and I went to Peppermint Grove Retreat for our honeymoon. There are only four chalets on the property and each of them has been furnished to perfection! Jarrah floorboards, a kitchen with everything you need, a very cozy king-size bed, massive bathroom complete with large shower and two-person spa, a gas fire and a private deck with a BBQ.
The chalet was spotless and the views were breathtaking! Our entire trip was extremely relaxing and even though we were rained in for two days, we didn't mind because the chalet was the type of place we wanted to spend time in.
Most days we'd do a little site-seeing, head out to lunch, then go back to the chalet in the afternoon to read and relax in front of the fire before making dinner and lounging in the spa with a glass of local wine. If you like animals or are not native to Australia then make sure you're looking out the back windows very early in the morning or at dusk - you'll see all of Australia's native birds (there are heaps of kookaburras), plus squirrels, rabbits and kangaroos.
The only microscopic bad points: not exactly wheelchair friendly as there are steps up to the front porch; very small mugs so if you like a decent cup of tea of coffee (both of which are provided by the way) then take your own mug; and also take a can opener if you have the need for one - the one provided is terrible.
As for Pemberton itself - it's quaint. Small and sleepy but quite picturesque with all of those beautiful forests. If you like wine head out to Salitage, Lost Lake Winery and Hidden River. Hidden River also have a cafe out the back with the most mouthwatering food imaginable. The King Trout cafe was also beautiful - the platter for two is to die for!
I'd definitely recommend Peppermint Grove Retreat to just about anyone wanting a relaxing getaway!