Hi Anna,
I'm a happy owner at Four Seasons Aviara. It's good that you are buying resale. Even so, don't pay too much. Tri West, in particular, has their listings way over priced...and they also charge far too much for closing costs. I bought my week through Matt Voigt at Stroman Realty and closed with Tia at Timeshare Transfer. I saved about 50% on the purchase price...and over 50% on the closing costs...versus buying with Tri West.
If you want to use a Four Seasons "approved" broker, then I strongly recommend Judy Rulli at Smart Choice Timeshare Realty.
www.timeshareaz.com She's extremely professional and helpful...and she has better prices than the other approved brokers.
It's easy to lock off your unit if you purchase a two bedroom. (There are a few one bedroom villas that obviously don't have a lock off feature.) Just call Four Seasons and request it. There's a fee, but I can't remember exactly what it is. It's less than $100, if I remember correctly. Another option is to split your week and use four days at one time and three days another during your season.
As for the floating question, the answer is that the vast majority of ownerships are floating. They float in one of two seasons: gold or platinum. Gold runs from the beginning of January through the first week of June and again from the middle of October through the end of December. Platinum season runs from the 2nd week of June through the middle of October. There are a few fixed week ownerships at Aviara, but not very many. The fixed summer weeks sell for a large premium.
The maintenance fees, as has been mentioned, are very high. They are about $2000 a year, not including the real estate taxes. If you buy an EOY, you will pay 1/2 the amount (or about $1000) a year...plus real estate taxes. The taxes are a little over $200 a year for a floating gold week. (This is also split in half if you buy an EOY ownership.) I'm happy with my ownership and feel that it is worth it, but it's definitely a luxury item.
Unfortunately, I have found the sales staff and owner services to be a bit snooty, inflexible, and cold. The contrast between Four Seasons and Marriott in this regard is positively stunning. While Marriott is all warm and fuzzy and happy to have me as an owner, Four Seasons is incredibly aloof and their staff has been borderline rude on a couple of occasions. They just don't roll out the welcome mat...especially for resale buyers. (Please note that this only applies to the sales staff and owner services department. The front desk staff, housekeeping, activities, etc. at Four Seasons have all been impeccibly polite, professional, and helpful at all times.)
Steve