The Stockyards are Emily's favorite part of Fort Worth! There's so much to do there. You can catch the herd (11:30 AM or 4:00 PM daily), the rodeo (8:00 Saturday nights), or Pawnee Bill's Wild West Show (Saturdays). On weekends, you can sit on/get your picture with a longhorn (free to get on, a small fee to get off, as their handlers will joke with you). For brunch, get the bottomless mimosas at Horseshoe Hill Cafe. For a great steak, try Lonesome Dove or H3. Los Vacqueros has great food and sometimes live music. The White Elephant Saloon and the Thirsty Armadillo are fun bars with live music. There's also a maze and a petting zoo.
The world's largest honky tonk is Emily's other favorite part of Fort Worth. They have line dancing lessons (Saturdays, included in the $5 daytime cover charge, appropriate for kids and adults), bull riding (never tried it, go at your own risk), live music, surprisingly good food, and some cool memorabilia - there's a bar within the bar that has tons of autographed guitars from famous musicians, and there are several walls of famous musicians' handprints (everybody from Blake Shelton to Bret Michaels). Billy Bob's is in the Stockyards.
Lots of food and shopping. Hyena's comedy club is here, and they always have really funny acts. There's a giant splash pad/fountain area (with a popsicle cart nearby - some of their flavors have booze in them). Mi Cocina has great food, and Reata has a nice rooftop patio (and comes highly recommended, though Tyler and I haven't eaten there yet). There are numerous hotels around Sundance Square. The Worthington Renaissance has subtle Western decor. The Hilton Fort Worth is a historic building (and the hotel President Kennedy stayed in before his fateful trip to Dallas).
The water gardens are beautiful and a fun spot to spend an hour or so.
Duck pond, two playgrounds, and a path by the Trinity River
Open 24/7, but you can't go wrong with their breakfast menu!
Don't skip the banana pudding.
Right off TCU's campus. Great burgers, shakes, and margaritas.
Tons of outdoor seating, right on the river. Somewhat limited menu, so check it out before you go.
#4 zoo in the country! There's also a water park attached (separate admission fee).