I think I cover your whole range
What State are you in, what sort of emissions regimen do you have to comply with? I ask because you listed the older vehicles (too), you looking for a non-electronic vehicle in particular? If that's not a particular issue I have to recommend the GMT800s. I think they're really in a sweet spot in terms of availability, price, condition and support in the parts / aftermarket. I already have a good bit of trouble getting some parts for my '85 C-10. Keeping the small block chevy running is easy, it's the emissions, fuel tank switch, stuff particular to the vehicle that is a problem.
There are a great many topics here from GMT800 owners, if you can search them out there's a wealth of info in them. As for what to look for, on the older trucks look fro frame cracking near the steering box, especially on 4wd variants. The LS/LM7 Vortec motors, there are a few things tha tcome with age / high mileage / rough environments, I've got most of them covered in my 'Hey Vortec Guys' topic -
http://www.expeditionportal.com/for...Vortec-Guys!-Sierra-pickup-Suburban-Yukon-etc
As to pickup vs SUV, depends what you rintended uses are. for 4+ people / family +dog its no contest. There's been a rash of Suburban purchases here of late, as folks move up thru smaller vehicles and more ambitious traveling plans. They really are a nice room solution for traveling and mild off-road and if you are desiring it, can be made more off-road capable.
/makes me wish I'd kept an index of the discussion topics about this, for handy reference. It comes up fairly regular.
in fact there's a guy on here right now that was just posting about selling a nice looking '86 Burb, might be just what you want
eta
http://www.expeditionportal.com/forum/threads/166527-Selling-my-overland-ready-built-Suburban