Picasso Museum - located in a series of very old houses in the old town this gave me a greater appreciation of his talents. I still don't understand some of it.
Casa Batllˇ - our first Gaudi building. Only saw the outside, but still impressed.
Casa MilÓ - incredible Gaudi appartment building. Well worth a visit to see the original rooms and the amazing roof.
Sagrada Familia - Gaudi's unfinished church. It will look amazing when they finish it in around 20 years. Meanwhile it's a work in progress. You can go in and go up some of the towers. I do wonder about the value of investing so much effort in a religeous building, but still admire the beauty of it
Barcelona Cathedral - a slightly older building (few hundred years) that also impressed. The view from the roof is great.
The rest of the city varies between elegant avenues and the cramped old town, but it's generally unspoilt by ugly, modern developments. They even have something resembling the London Gerkin.
There's plenty of shopping opportunities and the dining is excellent. It just takes a bit of adjustment as many restaurants do not open until 9pm, so you generally have to eat late.
The airport has the largest selection of shops I've seen outside Heathrow, but we only bough ta few gifts.
I would consider going back in the future to see if they have finished all their building. I'd also like to visit the Dali Museum that is a way out of town.
There are a few pictures on my Multiply site, but these are restricted to my contacts there. If you would like access then drop me a line.