Las Ramblas is the main tourist strip in Barcelona. It is situated that on each side there are stores, then a lane of traffic and in the middle is a wide pedestrian walkway. The walkway has kiosks, restaurant seating, street performers and pick pockets. I am happy to say I don't know anyone who was pick pocketed, but this area is known to have lots of pick pockets so you will need to watch your wallet.
Barcelona Cathedral is in the gothic quarter, across from my first hotel in Barcelona. It's free to enter and is strikingly different from Sagrada Familia, it's well - gothic. If you have more then a day or two in Barcelona it's worth a visit, particularly if you have seen Sagrada Familia. I went during a mass (does that count as going to church?) so I didn't have free reign of the church. But I was able to see the architecture which was very ornate and detailed. It was pretty dark inside the church, giving the feel of candle light. With vaulted ceilings and the dim light it had a VERY old feel. I'm pretty sure the lights were electric even if they looked like candles. There were many small and ornate chaples in the back of the church, heavy in gold and very detailed in their images. But I'm pretty sure the flat screen TV's were new though.
Finally, I want to talk about Barceloneta, the beach area of Barcelona. I didn't spend too much time here, it wasn't terribly warm and there is so much to do in Barcelona, but I wanted to see the beach here. It was a nice beach, and pretty long. It's strange to think of such a large beach in a city, and only blocks away from the heart of downtown.
The area has a lot of restaurants, I hear it's known for Paella, shops but not as many hotels as I expected. One of the girls I met on the cruise stayed at Hotel Arts (the tall blue one that was formerly part of the olympic athletes village), which is a very nice (and expensive) hotel. There is also a casino here. If you're looking for a relaxing stay in Barcelona this would be a nice place to stay.