Tough choice IMHO.
A couple variables for you:
1.) Decide if you plan to borrow. If you are not comfortable with doing it, then that may be a valid case for one resort.
2.) What size accommodations do you think will meet your families needs?
2.) How long you plan to stay with each visit? If you have a set number of nights per year that you will use. Be sure the contract will meet your needs.
3.) Will these nights be in on visit or multiple?
4.) If they will be used in one visit, would be willing to move to your other resort IFIF you couldn't get your entire stay in one resort.
Owning at multiple resorts isn't an issue if you have many points and don't have your heart set on key times of the year in single location.
150 points is great if you are staying in a studio for a week during most times of the year. If you decided to extend your visit beyond seven nights or get a larger suite, you may run into a point shortage situation. If borrowing isn't a concern, then no worries. If it is a concern, then you may want to lean toward a single contract.
A new policy that
DVC just put into effect (MS told me this morning): In the past, if you made a reservation at 11 months on contract A and then decided at the 7 month window you wanted to switch the points to contract B, you could do it without losing your reservation. The new policy will release your reservation if you want to switch points. At that point you will need to re-book the reservation with the contract you desire. By canceling the original reservation, the room is released into the system and could be booked by another MS rep or taken by the waiting list. Huge gamble. I did this one time in the past with banked points that were nearing expiration. I would have been in a pickle if this system was in effect.
If you have two contracts and plan to bank points, you cannot transfer banked points to the other contract. Another pickle I ran into. We were planning a
DCL and I was all set to transfer some banked points from one contract into another to book the cruise.
IMHO, I would not hesitate to have multi contracts in multi locations if you have plenty of points to achieve what you want and where you want. If not, it can be a hassle.
Best of luck!