My grandson has a hand me down Toyota Corolla with 190,000 miles on it. It just cost his parents $500 to replace a coil and plugs. He is also in college 2.5 hours away, but still makes the trip. It is always a dilemma when it comes to knowing when to cut bait and do different, but some of what you mentioned are normal expenses, like brakes and another seems like it might be covered by the transmission repair. The sensor is an easy fix, but you don't want to run it with the check engine light on because it might not be able to warn you of a bigger problem.
The idea that you don't know what you are buying when you get another is true. A 2.5 hour drive is nothing much more then a trip around the block at 97K. I'd fix it. If the engine has been maintained it is probably OK and half of your two primary repair expense (the transmission is the other). I'd go ahead and make the repairs. If you have a place that you can trust to be honest about repairs it would be advisable to take it there. More importantly no matter where you take it when they come out with the estimate always, always ask questions. If you don't know that the part is ask them what it is and what it does and is it something that has to be done right now. When questioned most will tell you the truth but they are counting on you to just shake your head, act like you don't have any idea what they just said and just to tell them to fix it. If the car appears to be running and operating OK, the chances are that it isn't all that urgent, but just make sure you ask a lot of questions.
Why does DH think it needs a new rack and pinion?