Some do also give credit I think … but when I’m deep in business travel, I end up with tons of Expedia points which are then doubled in value if used for one of the “VIP” hotels which has meant I’ve gotten very good deals/free nights on places I like to stay. Since I’m not 100% chain hotel anyhow … works for me.
Trivago lets you see all the on-line site rates (booking, expedia, hotel, orbitz, etc.)
I find searching with Tripadvisor compares the most sites and usually shows the lowest possible pricing on hotels, not to mention some of the largest sampling sizes for reviews. Always do a google search for online coupon/promo codes with whoever you decide to book with, I’ve earned an extra 15% multiple times doing that. Always remember to become a site member and log in before booking, more discounts turn up that way too 
Rolling the dice on Hotwire pays off too sometimes!