I would say that, if is doesn't place too much of a strain on your points - go for the one bedroom!
The ability to (potentially) save some $$ eating breakfast and other meals in your room is a plus. But, even more, I love being able to go to the other room (whichever that might be) and move around while the other party continues to sleep in the morning. Likewise, they can stay up later at night, while I can turn in early. And don't forget the washer/dryer in the 1BR - it comes in handy, also.
The one bedrooms at OKW are quite spacious - you will REALLY enjoy it!
But - to contradict everything I've just said, the "big minus" that others will often bring up is the fact that, by staying in a studio, you can either extend your stay, or possibly use those points for an additional trip.
FWIW - it's just my DH & I - no kids - and we <i>still</i> almost always stay in a 1BR, unless we're going over weekend nights.
Have a great trip either way!