Ooh, good question! Sienna's in Leederville is good. Haven't been there in a while, so not sure what the toilets/change rooms are like, but they have a cool playroom for the toddlers/older kiddies.

There was one time we went to the Amarin (does my favourite Thai!!) in Subi and I had to end up changing DS on the back seat of the car. It was our first restaurant outing with him and they don't even have a space in their bathroom on the sink to change him! LOL.

Although, if the toilets are clean enough I put the lid down and change him on that. Otherwise I go to the disabled toilets with my big change mat and change him on the floor (did that at Dragon Palace once).