Having made several hutches when my children were younger I would recommend :
12mm exterior ply for all solid panels. Keep all framework on the outside so that the rabbit can not chew it, it also makes it easier to keep,the inside clean.
Make the hutch higher than most shop bought hitches to keep,it nice and airy and also to let the children see the rabbit without having to crouch down. Paint the inside white which will show you where cleaning is required and looks much nicer as well.
Construct it in such a way that the floor panel/s can be easily removed for cleaning, this will also give the hutch a much longer life as the floor is usually the first to rot and so can be easily replaced.
Allow a generous overhang on the roof all round to keep the worst of the weather off, particularly at the front.
When constructing the sleeping area, double up the ply thickness to keep the animal warm in the Winter months.
Paint the outside whichever colour fits in with the surrounding area, I painted mine green.
Seal all the inside joints with exterior caulk before painting .
Constructed along these lines will give you a hutch that will last many years and will be as pleasant for the animal looking out as it is for the people looking in.
I hope this is of help
Cheers