If you have a meeting you do not want to miss then I would definitely arrive the day before; When I arrived in Lisbon (flying coach on CO) it took me about an hour to clear immigration; there must have been several flights at the same time and tons of people having difficulty filling the forms; I did not have an EU passport; if you have a EU passport or fly BF things may move quicker.

Lisbon is very nice; great seafood and fish; wonderful place to spend a day walking; You could also drive to Faro (good highways) and the views are very nice; November is a great time to visit the south of Portugal.
There are some good threads with things to do in Lisbon or about Portugal.
I have recommended in the past a hotel in Lisbon called Marques de Pombal; a very nice 4* hotel, great breakfast with really nice coffee included and it is right off the subway line and the bus from the airport. From there you could walk to the waterfront; I would not stay around the airport; Stay in the city and enjoy it.