We have one day dedicated to these two sights. I'm sure both are best seen in the morning before crowds arrive. But we cannot subdivide and must pick one over the other. Suggestions?
Time of year? In mid-summer, Parc Guell could be quite hot in the middle of the day.
That issue aside, I'd be inclined to go to La Sagrada Familia first, because I find crowds more bothersome at indoor sights--though churches aren't as bad as museums to me, because a lot of what you're looking at is above the heads of the people milling around.
We were there in January, and surprisingly it got quite warm during the day especially with no clouds in the sky. We booked La Sagrada tickets for about 2:30 and got to Park Guell well before opening. It was an easy bus ride from Park Guell to La Sagrada. It seemed to me that while it was crowded outside the church, the inside was not and even felt quite peaceful. On the other hand, Park Guell seemed to get more and more crowded as the day went on.
What time of year are you going? I suggest Parc Guell in the AM because it gets hot later in the day.
Thank you both for your responses. We're going the end of this April and have decided to go to Parc Guell in the morning with a reservation for Sagrada in the late afternoon.