gijoe --
It's been mentioned a couple times already by others, but I do want to emphasize that Carswell is not only in Fort Worth, it's actually on the far west side of Fort Worth. I'm not being pedantic, I just want you to realize that a jaunt over to Dallas won't be quick (it's over 40 miles from Carswell to downtown Dallas), especially considering the fact that the infrastructure / highway system hasn't kept up with the population growth in many areas.
Having said that, Carswell and Fort Worth have a lot to offer. It was previously a large USAF base, and still has many good facilities. I also agree heartily with emitex about visiting the Stockyards. (Don't be put off by the name of the area; it's much more interesting and varied than it sounds.)
I've driven between Fort Worth and Austin plenty of times, and while it may not be the most exciting of drives, it's not bad at all. It's about 190 miles from Carswell to downtown Austin, and it usually takes about 3.5 hours, unless you're driving in a rush hour. As far as stopping en route, I suppose it depends on what you're looking for. If it's just a quick meal along the way, there are plenty of towns and small cities with restaurants right along the interstate. If you have time to spend, Waco isn't a bad stop -- it's about halfway between Carswell & Austin. You can have a stroll around the Baylor University campus (they have a museum, too), or you can walk along the Brazos river (sometimes there are free concerts in the park nearby). There's also the Texas Sports Hall of Fame, as well as the Texas Rangers Hall of Fame. I don't know if any of that interests you, but they're just a few ideas.
Austin is a great city, though. Plenty to see & do there--Have a wonderful time!