Yes Founder's Plaza is on West Airfield Drive on the north side of the road, just east of the approach lights to 18L. It's basically across the street and down from the North Shuttle Parking lot, and if you get to Texan Trail redlight, turn around. Look for the picnic tables on top of a hill that's basically lined up with taxiway E.
Without a car, you could take the shuttle to the north shuttle parking, and then walk down the street maybe a quarter mile. It's northwest from the parking lot, across the street and down maybe that far.
The view from a room up high in the Grand Hyatt cannot be beat! Also, the exercise facilities on the roof of the Grand Hyatt have you walking the pool deck or on a treadmill against the glass that is looking down at the DFW