The DFW metroplex is huge. I've lived here 8 years. What part of this monstrous concrete jungle will you be in?
DFW has a little bit of just about everything. There are plenty of museums, zoos, aquariums, amusement parks, a million restaurants, etc. I'm not really into those things, so I can't really recommend any particular attractions. My girlfriend raves about the Dallas World Aquarium and the Dallas Arboretum & Botanical Gardens. Most of my free time is spent fishing or scouting and hunting the national grasslands that are about an hour or two outside of the city.
You will see when you get here, but I find the DFW metroplex itself to be relatively unattractive and I usually try to spend my long weekends and vacation days somewhere else like East Tennessee where there are trees and hills and a lot less people, cars and concrete.
Here is a list of the top rated Dallas attractions. There are lots of reviews from visitors that you can read to see what might interest you and your wife.
Things to do in Dallas
Here is a similar list for Fort Worth.
Things to do in Fort Worth
Oh yeah, there are two Cabela's and two Bass Pro Shops in the DFW metroplex if you get bored. There is also one of the greatest archery facilties on the planet out near Fort Worth. Cinnamon Creek Ranch is the name of it.