My girlfriend and I are flying into Lisbon, then immediately heading up to Porto for a few days, then heading down to Salema for a few days, then heading up to Lisbon for a few days before flying home. We do not want to rent a car (or take any inter-country flights) while in Portugal. How would you recommend getting from Lisbon to Porto, then from Porto to Salema, then from Salema to Lisbon? Any advice and/or recommendations would be greatly appreciated. Obrigado!