I have fallen in love with Portugal since I first arrived in Coimbra in 1994, in the course of a university exchange. This country has a rich history, and numerous monuments, cathedrals, and buildings testify the wealth and power that Portugal once held in the past. Modern Portugal is characterized by a a large choice of hotels, a good infrastructure, great food and hospitable people. Especially Lisbon has developed a lot and has changed into a trendy location for young people with bustling nightlife. The usually warm climate helps a lot, of course.
My personal favourite is Coimbra, a smaller town characterized by a vibrant student life and its university, founded back in 1290. The humanities faculties still reside in the old buildings on top of the upper city (“alta cidade”) whereas the engineering faculties have been moved to the new and stylish Pólo II, and meanwhile, all things related to medicine have been moved to Pólo III, due to an ever increasing amount of students.
I suggest to explore Portugal by car so that you can stop where you want as during your trips, you will have to stop frequently. There will simply be too many attractions, small shops beside the road and enticing restaurants on your way through Portugal.