[onewhippedpuppy]

I see you also get roped into this game? Every time someone in my extended family needs a car I'm the first one that they call for advice.

Your criteria look achievable, except for the sub-100k. I would throw out mileage concerns and focus on condition/maintenance and purchasing something of relatively decent quality. In my opinion mileage is nearly irrelevant with cheap used cars, two of my best ones had at/more than 200k. A few that come to mind for me:

Acura Integra sedan
Lexus EX - seem easy to find cheap despite being a Lexus
Honda Civic/Accord/CRV
Toyota Camry/Corolla/RAV4/Matrix
Pontiac Vibe - a Toyota Matrix with a Pontiac badge and lower price
Mazda Protege/Protege5 - seriously under-appreciated little sedan/wagon. I had a P5 and it was a great car.
Ford Focus - pretty decent cheap domestic car
Subaru Impreza/Legacy/Forester
Nissan Altima/Maxima