Dining in DFW is a beloved hobby, and pockets of great restaurants are spread all over the area. If you'd like to start a lively conversation with locals, ask about their favorite spot for Tex-Mex, barbecue, or pizza. You're unlikely to reach consensus but likely to learn a lot.
In Dallas you'll find plenty of restaurants in the West End Historic District. The area is easy to walk around, but it doesn't claim the best dining options. If you're up for more adventure, walk a bit north of the West End to Victory Park. Or move up McKinney Avenue, through the Uptown neighborhoods. When McKinney hits Knox Street, you've arrived at another restaurant-rich area that spreads east and west. From Knox, head east until the street becomes Henderson Avenue. You'll pass even more restaurants and will eventually dead-end into Greenville Avenue. Head north and you'll be in yet another restaurant-wealthy neighborhood—all within 7 mi. And that's just one sliver of Dallas.
In Fort Worth, restaurants and nightclubs are grouped around Sundance Square (bounded by Houston, Commerce, 2nd, and 3rd streets) and the Stockyards National Historic District, west of the Cultural District.
Dress codes are practically nonexistent—even the Rosewood Mansion on Turtle Creek dropped its jacket-required dress code in 2007. Some restaurants are encouraging longer stays (and higher bills) by offering and promoting more options—come for drinks in the bar, stay for dinner, and linger after in the bar or separate lounge area. Many higher-end restaurants don't serve lunch and are closed on Sunday and/or Monday.