It sounds like you guys are young and just starting out (you mentioned no kids yet but want them eventually). As a couple or later a couple with young kids, I think 150 is plenty for 1-2 trips per year. We almost bought in before we had kids, but backed out because financially, we were not in a place where we could pay cash, and that’s the only way we were willing to own
DVC. When our boys were 7 and 4 we were more established in our careers and bought 150 at Poly when it opened. We stayed in studios only and had plenty of space, usually using our points to do a 8 night stay at Poly each October. Now my boys are 13 and 10. Also, our own parents aging, we try to bring them with us when possible now, just to make memories while we can. So, We feeing a bit tight in a studio, especially with the teenager (and if a grandparent came, the studio was not doable at all), so we added 150 at Riviera so we could do a split stay between the resorts and book 2 studios at Poly and a 1-2 bedroom at Riviera (or, play around and book something entirely different at the 7 month mark).
I’d say 150 is plenty when you are starting out. It keeps the initial buy in doable and the annual dues more than manageable. Until you have kids and they grow older, studios are really just fine in my opinion. I foresee us adding a 3rd contract down the road so that as our boys have their own families we can book 3 bedrooms or multiple rooms for larger family vacations. We’ve even considered gifting each of them 1 of our current contracts down the road, so we’d want a 3rd for us. We’ll probably wait and see what the next resort is and maybe buy there. Or, if we don’t want to gift the contracts (meaning we keep our blue card status), maybe we’d buy a large resale contract somewhere.
All that being said, consider your current financial situation. When we first considered buying, it was at SSR and we were offered 160 points for about $13K. I’m a teacher, my husband was just starting his career, we had just bought a house and we did not have $13K to just pay out of pocket comfortably. 7 years later we bought 150 at Poly for just under $25K, so twice the price and less points. But we could pay it comfortably. It still pains me sometimes to think of how much cheaper we could have bought it, but overall I have no regrets waiting. We are not big SSR people, but huge Poly people and the timing felt right the second time around. In addition, the SSR contract expires in 2054 and our Poly in 2066, so we will have more years of use out of it with our boys and their families down the line.
That being said prices will only go up. So if you have plenty of cash to burn, go for it.

For us, we decided to find a balance of having only what we would use while not hurting our daily budgeting at home.