Here is a list of things you might want to do:
Dealey Plaza (of course) - Conspiracy theorists sit on the corners almost every day of the week.
6th Floor Museum - General JFK information and cool documents/videos.
Dallas World Aquarium - big indoor rainforest. Great for kids and adults alike
Dallas Arboretum - amazing outdoor space with tons of room for picnics/photos and great landscaping.
Nasher Sculpture Center
Dallas Museum of Art
Museum of Nature and Science
Dallas Holocaust Museum - small but powerful.
Southfork Ranch - if you loved the show, you'll eat this place up.
Highland Park Village - only for the serious shopper.
Galleria Dallas - ice skating, and shopping for just about every level of consumer.
Catch a concert/event/game at the American Airlines Center
Enjoy a fabulous meal in the Knox/Henderson area
A plethora of drinks and dining choices in Uptown
And around Dallas...
Arlington:
Cowboys Stadium
Six Flags Over Texas
Fort Worth:
Stockyards - yummy steaks and interesting history
Billy Bob's - a mecca for country-western fans
Science Museum/Omni Theater - a great kid's museum with lots of hands-on exhibits
Fort Worth Zoo - nationally ranked and worth the drive.
Sundance Square - clubs, dinner, drinks, festivals.
and if you don't see anything you like here, try the following:
Re: Visting Dallas?