If the doe will have a litter, I find it is best to have at least 2 x 3 foot cages. I raise Standards and have the does in 2 X 4 ft cages. This gives the doe plenty of room to get away from the kits once they get out of the nest box, because they will chase after her for the longest time trying to get milk.
Bare minimum for a rabbit without a litter would be 2 X 2 ft, in my opinion. Bigger is better, though!