I vote for Sunday as well, since technically its part of the weekend. Guests would probably be able to take less time off from work that way.
About your date. I am "tentatively" an 08.08.08 bride myself. Believe me, I know exactly how you feel!!!! I have been trying to find a place that is affordable for my guests as well as fits in with our budget for that timeframe.
Make sure you asks whatever resorts you are looking at if there is some kind of waiting list, just in case of a cancellation or something. I am still trying to decide if I want to change the date (I really dont want to ) But its getting down to crunch time, so I am going to have to make a move by the end of the year if I don't hear back from any of the resorts we wanted.
I'll keep my fingers crossed that you guys will find a resort you love, and soon