Well actually, I wish I'd stayed longer! Here's why - with a few pics by me and the friends I was with.
The place has about 7 palaces to visit, with large gardens/estates (we only did 3). As a playground to the Portuguese aristocracy from the 1500s onwards, it's got gothic gardens (a tower carved inside the rock at Quinta da Regaleira), lots of exotic plants (some Sequoia redwoods can be found in the Palacio da Pena ground), stunningly designed rooms (the blazons room with its ceiling painted with the emblems of the Portuguese royal family and many others, at Sintra Palace) and more. The Moorish Castle is from even earlier. I found it hard to edit down my pics for instagram!