One of the highlights of our trip to Barcelona was visiting the interior of La Sagrada Familia where you can observe this work in progress. Don't skip it.
We also enjoyed the Picasso and Miro museums.
Museo Picasso displays a lot from his earlier years which we found very interesting.

I'm just not that big a Picasso fan. I like him okay, but not enough to plan so many trips to his many museums, and his works are also seen in regular museums. I think I've been to at least 3-4 Picasso museums.

IN any case, I took the Bus Turistico and there wasn't any line at all to get on it at the Sagrada Familia stop. There was a huge line to get into that church, but none at the bus stop. This was mid-day end of Sept.

Now I do disagree that seeing the outside is enough. In fact, that was one of my favorite visits in Barcelona, the interior of that church. Wow, I've never seen anything like it. I visited the Pedrera, also, but not the other apt building nearby. I do think Barcelona is great for architecture, I agree with that, but I really liked the Catalonian art museum, much more than the Picasso.

There are lots of Spanish people on La Rambla, of course there are. Lots of them go there for a holiday, also, and to sightsee. Cabbies aren't always right. Besides, if you are a tourist, you are going to be with some non-Spanish people in lots of places in Barcelona. At the museums, all tourist sites, the dept stores, everywhere. I didn't find La rambla to be "a mess." Why say that? It's just an outdoor promenade with street vendors, no more messy than tons of other famous streets that people walk up and down.