Barcelona is definitely on my list. Are you allowed in the crypt where Gaudi's tomb is? Is the public allowed to sit in the pews, and just absorb the atmosphere? I get dizzy, standing and looking straight up. You entered and exited through the Passion Portico. I guess the guide explained the iconography.
We visited on a Sunday and purchased tour tickets for the first tour of the day which was at 10:30am. If you go to the 2:10 min mark of the video you will see people lined up outside the church waiting to get in for Sunday morning service. These people would have sat in the pews. I believe we could have also sat in the pews if we wanted to, others did. As for visiting Gaudi's tomb, I don't have an answer for that. I really don't know.