Wondering if anyone knows how to get marriott.com to give you the best rate structure for a given reservation when rate changes throughout your stay ...

For example if I am booking a Wednesday through Sunday room asking for AAA rates I would be expecting Marriott.com to offer:
-wednesday night at the weekday AAA rate (say 180$)
-thu-fri-sat nights at the 3-day weekend AAA promo (say 62$ per night)

But instead the system offers all 4 nights at a uniform rate of 160$ ...
(even though if you split the reservation weekday/weekend days the applicable rates are available and comply with the rate rules)

This makes a significant difference in total cost 640$ vs 366$ ....

Any idea how to avoid this ? is this better done over the phone and specifically requesting that the best rate combinations be used ?