Over 100,000 miles I'd have more faith in a Honda or Toyota than in a Nissan (or just about anything else). Some alternatives will have more space inside than a Prius. I'd suggest looking for a Honda Fit or Scion xB. A Toyota Matrix or Pontiac Vibe (essentially the same vehicle) might also be worth a look, but I don't like them as much as the related Scion.
This said, if you can find another Prius at a good price--more likely with gas prices low--it would also be a good choice.