My second car is an '03 eclipse gts just because that's what I had before the Z. Not very practical, but I've driven it through 10 seasons of snow, so it'll be fine (FWD auto, but I can manually move it to second from a stop in the snow, which helps a lot and I wish the Z would let me do that....not that I will drive it in the snow...).
Definitely take inventory of what practical needs you have that cause you to drive the car instead of the Z. For me, it's summer, and unless there is a storm around (which there isn't this year, as we've been VERY dry), I've driven my eclipse less than once a week. It sits outside, so it's basically constantly dirty.
- do you plan any snow/inclement weather driving? in Dallas, I doubt it.
- do you plan to tow the Z at all, or a motorcycle or ...?
- do you need the carrying capacity sometimes?
- do you offroad or regularly visit people on gravel roads that you don't want your Z on?
- do you go places and park places you'd rather not park your Z?
- are you concerned about mpg in the Z, and thus a second car is an economic choice?
- is the Z the default daily drive for you, or a weekender? is the second car a DD or the exception? This might help let you know how much money you should spend on the second car.
- will it sit outside or be stored under cover? (a nice looking car stored outside will be a source of constant frustration)
- what do you actually WANT to drive? maybe even a motorcycle will work!
All of these things and more will help guide what you get. A car, an economy car, a truck/suv, any sort of beater...
I would expect in Dallas, you'll drive the Z more often than not unless the MPG is a concern. That might mean your second car gets very little use, and probably shouldn't be a "great" car or new.
edited to add: Personally, I've never been a 'pickup' sort of guy. But now that I have a Z, the pickup makes a ridiculous amount of practical sense. I may go that route when my budget recovers from the Z weight.