The walk from the Sheraton Arlington to the Ballpark is about what you will have if you pay to park in a non-season ticket holder lot. They also run a local trolley to the various attractions around Arlington (Six Flags, Hurricane Harbor, etc.). The trolley is run by the city, not by the Sheraton.

Las Colinas (where I have officed for 14 years and where I lived for 5) is nice but its very much a "weekday" kind of place. It is a ghost town on the weekends and restaurants seem to open and close frequently there as a result.