Possibly looking into a tahoe or suburban/yukon, advice needed

So I'm contemplating a newer vehicle, but not going to retire the envoy. I'm pretty set on a body on frame and while I don't know what years to look for/avoid, I'm somewhere between 2007 and 2013, while 2013 is solely based on purchase price as they tend to get expensive after that.

Budget...low as possible of course..., but if I had to cap my spending I would like to keep it under $20K, more like $15K.

My main criteria is equal or better towing capacity than the envoy ( easy to do) and 3 rows of seating.... cargo doors is also high on the list, 4WD is not a must but very high on the list. A non-4wd would be my last resort.

The 1500 suburban has a paltry tow rating but I can get by with it, if I go with a burb/XL, I would like to be around 8K towing capacity or higher...no sure if the tahoe can achieve this. Hopefully my info on the 1/2 ton burb towing capacity is incorrect, but I'm seeing under 6000 lbs except for the newer models...something doesn't sound right, I thought they were around 7500 lbs or more.

Fuel economy...looking for at least low 20's on the highway while not towing. I believe the newer versions with the 6sp can achieve this so user input is welcome.

Will I need to step to a 2500 to get more than 6500 lbs towing capacity?

Would really like cloth interior but not a deal breaker. If I can get a LS trim with all the bells that would be great, cloth seats is a high priority but I won't let he perfect vehicle slip if it had leather.

Not sure what year the engines had issues, but all input and criticism is appreciated.

Why am I looking for one? I would like a newer GMT with more room and space for road trips and the ability to haul more weight if needed.