I've looked into then a little bit, but haven't gone too in depth with my research yet. They definitely seem like an affordable and viable option with a huge aftermarket. I used to be a tech for a chevy dealer and saw quite a few common issues, but would consistently see vehicles with 400k+ miles as well. I'll do some research and stop by the forum to see what you guys are talking about!
For what it's worth, I think most of the common issues have pretty good aftermarket solutions on the GMT800 and 900 platforms, and just about anything is going to have its own set of issues. Being that you're already familiar with the GM side of the house, that's all the more reason to get one in my opinion. You'll already know the strengths and weaknesses of the platform and be able to judge a good example from a bad one. I think you could build a hell of a 'burb for under 15k. Probably under 10k for what you want to do with it. I lucked into mine with low miles that had been well maintained for a really good price, but that was before the current used car bubble.
Your Tacoma is right between a Tahoe and a Suburban in length, so I'd lean towards a Suburban if you're looking for more room. In mine, I'm planning to build a storage and sleeping platform that goes to the back of the second row, and just fold the seats down at night when I need to get in and access it from the side doors. I did sleep in it with the second row up once and I needed just one or two more inches of space to really be comfortable. I'm 5'8" so if you're taller that's a consideration, but with the second row down it's a full 8 feet of space.