We went for the "Magical Nights" exhibit where you could see the house from 8:00-9:00 PM and then have a concert and drinks up on the rooftop.
There were a ton of people lined up to get in at 8:00 PM (not all with the music package), and the beginning especially felt very crowded and that you were being herded from room to room. Eventually the pack of people broke up a little so you could actually enjoy the architecture.
The concert on the roof was a nice bonus to the visit... allowing you to enjoy a bit of the sunset and breeze while overlooking Barcelona. Immediately on arriving on the roof, they offer you one of your two included drinks... a mimosa. You can avoid getting one and go to the main bar (opposite corner of the roof) for wine, sangria, or a beer. You should also do any visits to the gift shop before you make it to the roof, as it will be closed before you come back down.
Overall the house is an incredible piece of art and architecture... wonderful to explore and experience.More