But it seems to me that we could expect that the evidence of humanity would be evident to future geologists with even just a cursory examination millions or hundreds of millions of years from now...

Any landmass that had a city that wasn't completely recycled by tectonics would bear unmistakable signs- linear cuts through strata where roads were placed, concrete lined tunnels through mountains may be collapsed or backfilled but they would be obvious as long as the mountain wasn't completely eroded away. ceramics clearly made by civilization would be everywhere. Isotopic abundances would be wildly out of whack in the thin strata that covers our existence, but embedded in and below it would be trillions of artifacts made of unnaturally refined and assembled materials. Landfills, and that isolated pond 2 miles outside of town where people dump their old refrigerators are all excellent low-energy preservation sites.

If a gamma-ray burst suddenly wiped out all humans, cars might rust away, but the ceramic in the sparkplug would be found in large deposits where there were once roads and parking lots.

Blocks of stone imported from other continents would certainly stand out, the linear remains of water-pipes, optical and electrical cables would likewise raise eyebrows.
Glaciers might scour the surface put probably not that completely... unless we have a snowball-earth episode again... even then, there would be billions of tons of artifacts on the seabed off the continental shelf.