My daughter is heading off to college this fall and will be driving a 2006 Chrysler 300. The car has 242,000 miles. Everything seems to be in reasonable shape, for its age. I'm seeking advice for things that I should perhaps preemptively replace. We have had the rocker arms (cam followers) replaced back in 2012. I've replaced the front struts and sway bar bushings to get rid of a klunk sound that it had developed. Other than that, the car has not given us any problems.
Here's what I'm thinking of doing before she leaves in a few months.
Brakes
Replace the thermostat. It occasionally throws a code that the engine is too cool. I forget the actual code number.
Replace driver and passenger seat bottoms (cosmetic issue only)
Perhaps replace the alternator (I don't recall ever replacing the alternator)
Can't think of anything at the moment.

If anyone thinks I'm crazy for sending her off with a car as old as she is and such high mileage then I welcome that advice as well.

Thanks.

 

I don't think you're crazy.
My kid has been "sweat equity" paying for his soon to be his 2004 Sebring Convertible (5spd!). We've done everything you've listed and more, mostly be cause it needed it.
obviously, you need to evaluate your car and determine what it needs now, soon, and eventually, then decide when those items should be replaced.
in my mind, its anything rubber-based you could consider looking at first and replacing preemptively. rubber dies on time just as much on use.
you could replace things "just because", but then you could just say that about the entire car.
personally, mileage is something I don't fear, if a vehicle has been maintained.

Now I will say though... a 300 is a bit of a boat, especially on a college campus.

 

Thanks for the input about the rubber items. I may look at engine mounts also.
I like the ‘boat’ aspect to the car for safety. Her campus is a walking campus, so the car will sit in a parking spot except for when she needs to make a grocery run or come home for the weekend (2hr drive).
I would love to replace the exterior windshield trim just to make the car look newer but those trim pieces are very expensive.