When people come to Dallas for Meetings it could be anywhere in the Dallas/ FT Worth Area. There are quite a few things to do but if you are in Dallas as in Downtown Dallas you will need a car. The bus and train are getting better and if you already downtown a train ride over to Ft Worth could be a different way to spend the afternoon. I've never been to the Dallas Stadium for a football game but have done the tour a few times and loved it. Plus have been there when my company had our dinners catered there. It would be great if your wife company was doing that since they would have transport all worked out, but that is usually a short 30-45 min tour. The Main one is longer and actually pretty nice.
Mesquite might be having their rodeo's going on which is a short drive, The Los Colinas area has a few nice photo places. also short car ride. To get some good pictures of the downtown area head over the new bridge going a little west. There is a nicer dinner place called "Smoke" Great tequila also. On their patio or the attached hotels is a pretty good view of downtown and will give you ideas for other spots. It can be a little dicey of an area depending on what you are used to. Oak Cliff is some older builders, and nice spots, but not an area I would send people to on their first time here at night.
The JFK's book tour that someone mentioned is fun, hang out at the grassy knoll a bit. Klyd Warren Park is a new park downtown that has different events going on, so you would need to google the dates you are here. I do the free salsa in the park they have in the summer, food trucks etc. You can pick a nicer downtown restaurant and play the "date or Daughter" game. Is that lady his date or daughter???
Take the train to Ft Worth, see the stockyards, head over to billy bob's. At Sundance Square they were doing some weird crackdown a little while back where security people were coming up to people taking pictures and asking them to leave. Not sure why or if that's still going on.
For a longer drive head over to Fossil Rim, where you drive safari style to see different animals and on the east side of dallas, are a couple of Big Cat refuges also. Can't think of their name off the top of my head.
So it really depends on if you are going to have a car, are looking for great photo places, or just want to hang out and have a little Texas flair.
---------------Camera, Lens, Flash stuff.. but still wanting more