Researching auto rentals in Milan. I want to avoid the airport but on the aggregator there are several other locations that show up but no map so I've no idea what would be a good location. Suggestions?
Grab the address and copy/paste into Google maps
In Italy, town and city centers have camera-controlled zones [ZTLs] for residents only, incursions resulting in heavy fines:
http://driventoit.blogspot.com/
So the airport may be more convenient. However, the key question is where are you going next.
That link to the "Driving in Italy" posting was incredibly helpful, and also quite amusing in places. If you are making the questionable decision to drive in Italy, look at that link, and probably make a copy