I have a 1994 Mazda 323 that I bought used in 1996 and now has over 200K miles. I am facing the choice of retiring the beloved old girl for another car, or exploring what it would take- and cost- to overhaul her. Is it worth it, beyond the sentimental factor- to keep this car running after so many miles. She's had three radiator replacements, two water pumps, and two a/c overhauls. Thoughts, anyone?

 

So you drive just about 11000 miles per year. If you have records of your expenses you can figure out how much this vehicle cost you per year. If it is less than 1000 per year I think you did well.
Now do you think it will continue at this rate? I would say it is quite possible. I would continue driving it as long as it is possible to do it under 1 grand per year. But expect replacing suspension parts and brake parts. I am sure you replaced tires and brakes before.
The engines last longer (250K or more) if they had oil changes on schedule.

So have a mechanic look it over and give you estimates on fixing things that are safety related. That way you can see if it is time to look for a replacement.

Once you have that you could say I fix thing 'x' but I will junk it when things 'y' or 'z' go kaput.

Meanwhile you look for a great oportunity on the used car market, ready to pounce.


Oh, I am doing just that regarding my minivan. I have a shortlist of vehicles I may pounce on.

 

It's almost always cheaper to repair than it is to replace. New cars are expensive, and getting more so, and they devalue greatly in the first two yrs.
That said, the 1st gen 323's are nothing really that special. As you'd said, and I do completely understand, that the sentimental value may out weigh what the car is actually worth to someone else. That would certainly have to be your choice.

A number of years ago, I was faced with the same dilemma, only with my 1980 Honda Civic HB. I LOVED that car and she was really very good to me over the years. But w/187k on the clock and rust developing everywhere I had little choice but to get rid of her. She (Inga) was of no value to anyone but me, but I loved her and was very sorry to see her go. I had many happy times in that car, and some busted knuckles too.
A second gen Civic is no more valuable today than is a 2st gen 323, so it has to be your choice.
You'll need to size up the car, especially the body and frame, because if those are going, don't even think about it. Mechanical stuff can always be repaired, but a weak or rusty frame is another matter. The cost would kill you in the end.