we went to the stonehouse for valentines night in 2006 and had a great time. they had a live singer/guitarist who was pretty good.people got up and danced near the end of the evening.we got talking to some people who ate at the stonehouse everynight of their holiday!all the ladies got a longstemmed red rose with the bill! it was a nice atmosphere.we always have a meal or two here but haven't been for valentines day since.

The Marinha Dourada usually have a Valentines Theme every year. Last year it was really pretty with red lit up love hearts going from building to building. Really nice at night when it was all lit up. (Might sound a bit tacky but it wasnt)
I would go somewhere like After 7 or Souymens Kitchen which are both first class restaurants.

Most places do valentine night the year we where at M/D was good,but they all celebrate it where are you stopping.

My rec would be Le Restaurant Francais in Baga. Excellent food, great ambience.