I find the opposite: the rate in Concur/Amex is almost always higher than booking direct with a AAA rate, corporate code, or any type of decent promo code.

The only offhand exception I can think of is when you have a discount associated with a credit card - like an Amex FHR type promo or the old Citi 4th Night Free booking through the "Thank You" portal. (Perhaps Chase has something similar?)

For me, the points trade-off is that Marriotts are usually more expensive across the board than a decent boutique hotel or regional (non-global) chain, even in large European cities where finding reliable reviews of local boutiques is pretty easy and you can generally trust that it's a decent product.