The midwest lifestages are great cages for the doodles. I have a 42', but the 48 is probably better if you think yours may be large. I have a 6 month old that sleeps in my room without his cage now, but still crate him when I leave to go somewhere. You never know what a puppy can get into.
The length of use depends on your doodle in particular. I have had my other LD out of his cage since he was 7 months old. He never chewed, and is always well behaved. Some cannot be trusted at all until over a year or so. The midwest cage is collapsible, and it is wire.
I got my labradoodle at 11 weeks also. The cage I purchased is a wire, life stages (I think it's 36 X 24 x 27), it has the double doors and a divider. I've yet to use the divider because she only had an 'accident' the first two nights and she seems to do well in there. During the day we open both doors and she does go lay down in there on occassion. Good luck!
At the bottom of this link you will find some good info on crate buying...I use both plastic and wire. Wire gives more visual space for your puppy, and more air circulation...plastic gives more of a "den" effect.