I guess I would say that the Astro is fairly solid IF you get one with a generous extended factory warranty. Reliability "issues":
--> replaced front pads at 20K
--> had TWO experiences (one inside and one outside of standard factory warranty period) with "bad ignition" wires (>$450 each)
--> transmission went to mush around 35K miles (fortunately just barely within warranty period).
Very roomy-- can accommodate lots of people / car seats (though the front seats are a bit cramped for those long legged folk). Decent acceleration. Rides high and considering its size, one at least feels safer on the road.
Considering sub-par reliability, definitely consider an extended warranty.
This sounds just a bit odd. How can bad ignition wires cost $450? A set of quality wires runs $30 or $40, even Magnecor racing wires are under $100. I would say this reflects more on the mechanics you use rather than the vehicle.
As far as brakes go, 20,000 miles is a fair lifetime for pads on such a heavy vehicle. Also, brake wear is affected by the driving pattern and loads carried.