I run a full sized blazer, have owned suburbans, s10 blazers, Extented cab f-150, still have a tahoe, etc.
A full sized Blazer is great. I feel like I can go anywhere compared to my old extended cab long bed f-150 or even the suburban was pretty darn long. You can sleep two in the bed, more if the kids are small, but it would be tight. As far as cargo room, it is drastically more than a mid sized suv. Sure the wheel bases are similar, but the amount of room in a 6 foot truck bed (which is what the k5 has) is simply far more than other SUV setups. The Tahoe would also make a great vehicle, I love ours, though it's set up for momma driving.;-) The vortec rocks too.
You will pinstripe a full size with brush, so don't spend a bunch on paint.