I was a timeshare salesman at HWP for four years.
First of all, second or third floor. Preferably third. No matter what building.
Buildings One and Seven have the best view, hands down. (But One has more traffic noise than Seven. Neither is particularly annoying, and traffic essentially ends at sunset). Building Seven is preferable because it's set back from the road. But you absolutely do NOT want a first-floor room in Seven. You'll look at the snack bar.
Building Eight is also good, but the last unit (824, 834) is the best, followed by 3 then 2 then 1. Again, second floor or better is preferable.
Buildings Two, Three and Five have the worst views, and Building Four is closest to the airport, but has good views -- except the corner units between three and four -- 414, 424 and 434. Building Six is closest to the pool. That's a deal breaker for me, but a lot of parents want to be able to watch their kids from building Six.
Don't let the airport scare you. Only a couple jets take off and land each day. You probably won't even be in the unit when it happens. All the rest of the planes are prop-jobs, no big deal. (EDIT - And if you're flying in with little luggage it is no big deal to carry your bags over to Windward. I did it several times when I was working there. I'd fly to the Bahamas for the weekend, then arrive Monday ready to work. It was great being so close to the airport. The taxis will add a $10 per person surcharge no matter where you're going from EYW. If you can carry your bags 1/6 mile, it will save you $30. Backpacks, if at all possible. Trust me on this.)
The units themselves are GORGEOUS. Doesn't matter which one you get, they're all excellent -- except the handicap rooms. The counters in the handicap rooms are at wheelchair height and rather annoying. The only problems you'll likely to encounter are difficult sliding doors and broken jacuzzi tubs (guests are constantly filling them with bubble bath.)
The beach is a one-mile walk. Whoop-dee-doo. It's a beautiful walk. That's what we all used as our exercise path every day.
Don't have any food delivered. Food delivery in Key West is invariably awful. Do have a bike delivered. Bikes trump cars in Key West.