I know everyone's different, but here's my thoughts - We've been fortunate to be able to stay at a few deluxe resorts (CR, GF, and Poly) when my husband goes for work, but we only get to stay for 4-5 days each trip. I've found that when the trips are shorter, I want to spend LESS TIME relaxing at the resort and MORE TIME in the parks. The resort becomes more or less a place just to sleep. So I have hardly gotten to experience the resorts to their fullest. I imagine if I stayed longer, I would take the time to relax by the pool, drink coffee on the balcony of my room, or take in the sights of the resort. But on a short trip, it's hard to spend any of my limited time away from the parks. So I would vote for a longer stay, because when I have a short stay, I don't want to spend much of it at the resort, anyway. Of course, that's my experience, and this may or may not be the case for your family depending on how you spend your time on vacation
Someone did mention renting DVC points, which in my experience, is a very affordable way to stay at a deluxe resort for a very reasonable price (depending on what type of room you need and when you go.) We are going this December and are staying at AKL for less than what we would pay at the Value resorts!
Happy anniversary and I hope you have a great trip!