Roader mentioned the thermostat housing/tube - I believe they are plastic and can crack eventually, so probably a good idea to change that at the same time.I was actually going to ask about the radiator but figured that was too much for one post. Aside from the T stat and radiator, what other parts are necessary? I imagine there are some hoses and clamps. Looking at some posts on here, it's a bit of a PITA compared to other radiator changes.
The main hoses are the upper and lower radiator hoses. While I almost always try to buy quality aftermarket parts to avoid the "OE" branded premium, for whatever reason, the OE Toyota hoses are significantly better than anything in the aftermarket. If you're planning on replacing with some inferior hoses, I'd probably suggest that you just reuse the old hoses, since I think they should last a bit longer than 109K. But, the best option would be to replace the hoses with new OEM ones. I'd probably buy the OEM thermostat tube just to ensure you're getting a quality one.
I imagine you could probably reuse some of the hose clamps, but it might be a good idea to get all new ones while you're at it. Stick with the spring type clamps - the worm/screw type ones don't allow the hoses to flex as much. If they're not rusted, I think you should be fine reusing them. If you need to buy new ones, I'd also advise OEM ones - despite rarely buying OEM parts.