Been to both as Diamonds... as well as having stayed at the airport location pre-flight and as a "fill in" (since the Regency was sold out (staying the night before and after airport there). This review is for a stay in early February 2014 for Hyatt Regency (formerly Peabody). Stay was very nice. Diamond recognition.. had parking and spa access waived as well as resort fee. Was staying on a C+ P the first stay, total points the second. Did regular parking and had the golf cart give ride to parking structure. I understand now they don't waive the resort fee for Diamonds as well as parking. You may want to factor in these charges when deciding on hotels. Regency is a convention hotel... DH was there for one at the convention center and having the convenience of walking over was nice. The weather wasn't suitable for lounging at the pool (had a cold snap) and there was mixed info about classes in the gym. Didn't eat in any of the venues other than the Regency lounge.. at that time still staffed by former Peabody employees.... had a hot dish each evening... a nice spread for breakfast. It was a very comfortable place to spend time during the day. Things may have changed since the hotel was still trying to figure out it's place as Hyatt.

Airport -- typical airport hotel.. Have had mixed experience with Diamond recognition... usually got a basic upgrade though sometimes amazing comps too (so no complaints either way... usually one night stays and mainly looking for a clean, comfortable place to sleep). Have had decent quick late night bites at McCoys -- though last time somewhat lacking in service. Usually have a great breakfast at Hemisphere... usually having buffett suplemented with ala carte beverages (smoothies) and fruit (mixed berries that had been offered at buffet in the past -- if there's something you'd like ask the waiter, will probably be accomodated with a "no problem, your diamond, it's our pleasure"... never a bill (though you MUST get a voucher at check in). The last two times staying here the buffet has been slow in having items replenished (and not that it's been 5 mnutes before closing) as well as a very slow kitchen for omlettes etc (not sure if it's the kitchen or waitstaff since items served are not quite hot when served). Either way it's a better choice when the price is right vs. staying with relatives in the area.
YMMV
Enjoy
Carolyn