Me and my family had a great time staying at Michelle and Ian's cottage whilst in Triabunna. It's only 10 mins walk from the Maria Island ferry and local bar/restaurant and is a very clean and tidy place. We loved the thoughtful extra touches too!
One thing to note on your stay in Triabunna... a lot of the local restaurants shut quite early (7-8pm) and so does the local shop, so plan to eat earlier in the evening or bring dinner with you to cook in the kitchen at the cottage.