You are in a very good place to have take the Trinity Rail (commuter) Express into either downtowns of Fort Worth (Intermodal Center - ITC) or Dallas (Union Station). I'm fairly certain the Holiday Inn will shuttle you to the CentrePort station about a mile away - verify they will also provide the return.
One note of caution - because it is a business commuter rail, it's weeknight schedule stops around 9:30p leaving FW and 11:00p leaving Dallas. Unless you want to pay a lofty taxi fare, you do not want to miss the last trip.
www.trinityrailwayexpress.org/newweekeb.html
If you plan to go to only Dallas *or* FW, you would want the
Day Pass, 1 ZONE TRE (east or west), $7.00
If you decide to go to both cities, you'd need the
Day Pass, REGIONAL (2 zones), $10.00
In Fort Worth, there are a number of restaurant and entertainment options in the walkable downtown area of Sundance Square - take the circular Molly the Trolly.
http://www.sundancesquare.com/
mollythetrolley.com/downtown_get_around.html