This is what we have done for many years with our two contracts....bank one contract's points and borrow from the other to make a reservation. It works well since our two contracts are pretty much the same number of points. So your plan on buying another 150 point contract should work well if this is your intention.
Since F&W is a big part of your plans, I would definitely purchase at either BWV or BCV. BWV has the great Standard View rooms which are an amazing way to stretch points as long as you are not worried about the view from your room.
We originally purchased at VWL and then bought another similar sized contract at BWV. VWL was purchased because we loved our stays at WL...the theming, the majestic lobby, the music, the ambiance all were perfect for our family. We purchased at BWV because we stayed there once and really enjoyed the resort, the Boardwalk amenities, and the convenience of walking to two parks. And again, the Standard View point schedule is such a bargain! It also helped that we didn't find the big Stormalong Bay pool at BCV to be as much of an attraction for us as it is for so many others.
For you, I would definitely purchase BWV or BCV. I know that the expiration dates are in 25 years, and if you are fairly young I can see why that would be a consideration. But if you buy any other resort, you may have many years of trips to F&W when you are thinking that you wished you had purchased one of those two resorts.
Good luck!