We aren't yearly visitors to WDW (I wish!), but we do go more often than anyone else we know. We are going on our 7th trip next month.
Our longest stay in WDW was a 9 night 10 day trip. By the end of it, DH was Disney'd out - but I could have stayed even longer.
On average, our trips to WDW are 6 nights / 7 days.
Our longest vacation was a camping trip we took in Pennsylvania. We did 2 weeks (14 nights) when we had just 3 kids. My mother was my babysitter while I worked and she went to Italy for 2 weeks so I HAD to take the time off anyway. DH couldn't get the entire 2 weeks off from work so I did the first 7 nights just me and the kids, and DH joined us for the second week. My youngest at the time was in diapers. The campground was right on the Delaware river and had its own pool and canoeing, playground, etc. We took a few day-trips to sightsee some of the local towns too. I loved it!