I am prepping to do the same thing. I am doing a truck, so it will be somewhat different than your suburban.
I pulled the gauges, but not the column or the seat because the column is pretty easy to work around and none of the wiring runs under the seat, inside the cab. The dash itself is spot welded in.
My harness has:
1. fuse block
2. A bundle of wires the run into the dash for the gauges/radio/hvac
3. A bundle of wires for the engine
4. A bundle of wires for the front (lights, horn, etc)
5. A bundle of wires for the rear (fuel sender, lights)
Each of those bundles (except the dash harness) goes through a grommet in the firewall, then is routed outside the cab to the correct locations.
I intend to lift the truck to run the bundle to the back, but leave it on the ground and work from the top for the rest.
