Please help us to decide whether to rent a car in town in Lisbon or go back to the airport to pick one up for are other stays around the country. We would be returning the car 10 days later to the airport. Does anyone know if picking a rental in town is a hassle? Also, is there any car rental agency you specifically had good interactions with? Thanks!
Take a look at Auto Europe. I would never want to drive in Lisbon. Lots of one way streets and chaotic drivers, not to mention trams on some streets. I would look at wherever you are spending your first night and rent there, if possible.
The airport is very close to the city center, making it convenient. This being said, most car rental outfits in Lisbon are near Marques de Pombal square which has direct access to the motorway, so it is not that bad.
We rented a car from Europcar in the city, it was very easy and closer than the airport, an easy 5EUR Uber from our VRBO near Praca Commercial. Made our reservation on Expedia.
Compare zestcarrental.com for good prices and options.
I found that picking up or dropping off at airport may incur an airport charge or a shuttle to off-site to pick up cars. Best prices usually at the various car rental offices just outside of airport with easy exit out of Lisbon e.g. to Vasco da Gama bridge. Very easy to catch a bolt from a downtown hotel to the various car rental companies if you don't want to drive in the city. If you don't mind driving in the city, some Zest rental companies will drop off car at your hotel.
Did a quick look on expedia for random 10 day rental.
a)downtown pick up and airport drop $343
b) airport pick up and drop off $243
Plug in your specific dates to see which works best for you when you are shopping around.