I wasn't planning on chiming in because there are already great responses but I have to agree with Sammie on this one.
Make sure you LOVE your resort. That is the only guaranteed thing in your contract. They could change their rule the day after you purchase saying that you can only stay at your Home Resort for the life of the contract. No exchanges, internal or external. And if you end up not liking it, your only options would be to grin and bear it for the life of the contract or sell your contract.
So please pick your HR really carefully.
And you mentioned that you're a young family. Buying
DVC is like trying to see your future. For now you think a studio here and there makes no difference. But when your kids get older (as another PP said), you might realize that you need that extra space, extra bathroom (only on newer DVC resorts) and washer/dryer...

Or that waking up to savannah view is the only way to vacation, or chilling on the boardwalk everynight is your idea of heaven, or that the pool at BCV is the only place to go.
If I were you I would wait until you see the different resorts DVC has to offer. Go check out all the resorts that you might be interested in before you purchase. Resale points will always be available. And as Chuck have mentioned, exchanges to cruise etc. is not the best cost wise. Maybe after you see all the resorts you realize that getting more points thru resale is worth not having the exchange option.
Good luck deciding!