Please note that the views expressed here are based on reported personal experiences and are not "official" views in any way.
Probably the best local resource has got to be the revitalised Bedgebury Pinetum, which with the £1m injected into it by Sport England, has transformed itself into a fantastic off-road cycling centre, plus playgrounds dotted in the forest for smaller and larger kids. The pirate ship, giant spider's web, and battering-ram style rope swing is a favourite with all the family.
If you haven't been yet - go now! Bicycles can be rented on site . The visitor centre has tea, coffee and jolly good cakes.
Bewl Water has acres of space, beautiful scenery, a good adventure playground with a huge long slide, a brand new toddlers' play area, a children's fishing pond and steamship trips out onto the reservoir (summer only). The latest addition is a nice sandy beach in front of the visitor centre - quicker than driving to Hastings and better sandcastle sand. If you're up for it, there's a 13 mile walk round the reservoir - you may want to take bicycles. There is a cafe /restaurant and toilets next to the car park.
The nearest indoor facility in the area is MinorMania at Bells Yew Green (a short haul along the Bayham Road). Since its revamp in 2010 this indoor play centre for kids aged up to 10 or thereabouts has become very popular with kids and parents alike. Coffee drinkable, but food very basic. Wifi. Take earplugs.
There are a number of weekly music and movement classes for toddlers and small children - Jo Jingles operate out of Goudhurst and Matfield village halls.
Lamberhurst has a new fabulous children's playground on the fields behind the village hall. It has a zip wire, swings, slides etc with separate areas for toddlers and older children. There is also a soccer wall.
Drusillas Zoo near Alfriston is a fabulous day out for the kids. It's a little pricy for a one-off day, but if you decide to go several times, their annual membership fees look very attractive.
The Hop Farm at Paddock Wood is also a bit pricey, but has plenty to keep kids happy for an afternoon - the heavy horses are wonderful, and there's usually a number of other animals around to say hello to. There's a cafeteria with a variety of rather unhealthy food, and a great play-cage for 2-8 year olds.
WE NEED TO HEAR YOUR EXPERIENCES - please send to firstname.lastname@example.org