I've done 6 nights, 5 nights, 8 nights and what should have been 7 nights in the last few years.
My next trip, god willing, is going to be 2 weeks or as close as I can get to it.
Cost is a huge factor to a lot of people because it's super expensive as everyone knows. So any time you can get down there is special. If money is not a barrier to entry, I have to say 10-14 days is a pretty good sweet spot. I think the more time I go down there, the less rush I'd feel for my normal park days and the trip can be more relaxing.