Thinking about selling (almost) all my 35mm gear...

And...Good luck on your retirement and you travels. It will be great.

After deciding to sell you stuff and how, maybe we start thinking about which cameras you keep and how many.

When buying, oft quoted advice is to buy from a reputable dealer. When selling, oft quoted advice is to avoid dealers.

Where are the dealers supposed to get their stock from?

If you want your cameras to go to a good home, then imo selling to reputable dealer is the way to go. Anyone that pays full price for a camera is more likely to treat it well.