Most of what you ask for in options is a matter of preference, what you are used to having, and what you will be using the SRX for. That is probably why so few responses. Tough to advise.
Engine choice: Browse through the first few pages of the First Generation thread listings on this forum and/or do a forum search on V6 and V8 engine issues. V6 oil consumption, timing chains. There isn't much out there in V8 Northstar issues. There is a wealth of knowledge on this forum and guys willing to help because the folks with 2004-2006s have had the time and the mileage to let you know what has shaken out for them. There is a thread out there on "how many miles do you have on your SRX........." Your choices of pre-owned vehicles go way up with the V6 because far more were sold, and the higher prices on the V8s reflect that. In my opinion, the V8 is bulletproof if it has been maintained properly. This is the second V8 Northstar I have owned, not one issue. Fuel mileage does not seem to be critical for you, so you can go either way. The V6 will squeeze out an additional 2 mpg, and the V8 is rated around 21/15, achievable in real life.
Daily driver, parking lots, the Texas sun/heat, and the number of passengers when you get to your kids' place: I would suggest you look for one with the optional additional rear air conditioning unit and one with third row seating......both found together in the "Utility Package" but were available as stand alone options. The third row seating isn't great for larger people (2), but it beats not having the capacity when you need it for the shorter runs when visiting the kids and possibly grandkids. It is powered and folds flat into the floor when not in use. The Utility package also comes with heavy duty engine cooling system and a power steering fluid cooler. Personally, I love the UltraView roof and power sun shade, and use them daily. The UltraView is about as close to open air driving as you are going to get in a fixed top vehicle, it is massive.
With both wife and you driving: The optional power adjustable brake and accelerator pedals; tilt steering wheel. If you want to go a bit further, the Premium Seating Package which includes 8 way power front seats, two power lumbar points for each seat, the memory seating and mirrors, and the heated seats. My wife and I take road trips, and this stiff comes in handy daily or on the road. Wife says we will never be without heated seats again, third vehicle on which we have had them, used a lot, heat where it matters before the engine warms up.
Color: Texas heat? Sitting in the sun? Lighter colored interior and exterior will make quite the difference. Add passengers when you get to your destination, even more so.
More snow than expected 4 years in North Texas: The pre-owned 2007 my wife and I picked up a year ago is an SRX4 AWD. Never had AWD before, but it brings functionality beyond an element of safety and peace of mind if you are worried about the snow. We average annually 42 inches of snow in the Northeast, 90 so far this Winter including two blizzards. If my wife gets stuck in this SRX, she has to be really trying.
Optional rear DVD, NAV, and the Home Theater surround sound: We have grandchildren and take them on long road trips (some over 1,000 miles each way). Rear DVD = the best invention since beer. Not a peep out of them from start to finish as long as the batteries in the wireless headphones don't die. Beyond movies, we use the surround sound setting also for CD and XM satellite radio. There is actually a DVD over-ride code that enables the front seat passenger to watch movies as well (works in the 2004-2006 model years only). A forum search will get you info on that.
Other: If you can get an extended warranty from a reputable, long-standing, financially sound insurer, get it. Cheap at twice the price if you keep the SRX for any extended period. There are a lot of gadgets that can go South on the SRX, and every trip to the dealer on your dime won't come without a hefty price tag. I think it is worth it just for the engine and drivetrain peace of mind, especially on a pre-owned vehicle.
Carfax (title search), dealer maintence and repair records, and your private mechanic's second opinion on the vehicle condition.
Good luck on your search.