Curiouser and curiouser....and apparently II's answer is even curiouser than that. I asked them as well and it turns out that when you make a request online the dates you pick don't really matter - which is why you can't pick a 'latest travel date' less than 7 days from your check-in date even though you might want to arrive on a particular day. If you actually need to check-in on a particular date or dates you need to call them. From their response...
"Please be aware, if you review your request online, you will see Thursday as a checkin date. Our calendar week defaults to Thursday as the beginning of a week, as many resorts have Thursday as their checkin date leading into the weekend. If there are only certain dates you can checkin, please call our office. One of our agents can go into your request and handpick dates for you."