A formal gathering is a little different from a traditional one. In a formal gathering the meeting has a set agenda and schedule to keep. People may have time to socialize but there will be specific times reserved for eating, education, or specific topics of discussion. Formal gatherings include management meetings, strategy sessions, and board of directors meetings.
The formal gathering venue should be well-equipped for the meeting you have in mind. For a board meeting technology is important. Does your venue offer projectors, audio-visual equipment, high-speed wireless internet, and other connectivity features? If breakout sessions are a part of the agenda then separate rooms close to the main meeting hall are necessary.
Coworking spaces are a popular choice for formal gatherings, as are hotel conference rooms and library conference spaces. These venues offer the right technology for presentations and the sharing of data. Most offer flexible rental rates by the hour or day. And most are located in or close to downtown Dallas, especially coworking spaces. What sort of gathering do you have in mind?