We rented seal beach cottage for our first family holiday as a family of five (toddler aged 2 and twins aged 9 months). It was a brilliant holiday and the access to the forest and beach allowed our toddler time to explore outdoors whilst the twins napped in the cottage.
Louis provides a high chair and toys for our daughter to play with in the meadow (frisbee, skipping robe, balls etc). And she even offered to babysit for my husband and I to explore the grounds.
The fern trail and swings that everyone mentions are delightful. What we loved most was the gorgeous sunsets and the tranquility of the private beach.
Mayne island is lovely; lighthouse point, Bennet bay, the Japanese gardens etc but we could have had a fantastic holiday without even leaving Seal bay.