recommendations for an overnight stay somewhere between Porto and Sintra

I will be finishing Rick Steves' Portugal tour on Sept 27th in Porto. I have three nights before flying out of Lisbon on the 30th. I plan on spending my last two nights in Sintra and driving to the Lisbon airport for my flight home on the morning of my departure (flight leaves at 11:45 AM). I need a recommendation for the first night - after the tour ends in Porto. I will be heading toward Sintra, and have thought about Nazare, Peniche, or Sao Martinho. Does anyone have a recommendation? As part of the tour, we will be spending a little time in Nazare, but not sleeping there.

Thanks,
Linda