Just got back from 5 days in Barcelona. What a great city. Will give you a brief run down on where we ate and some general impressions. please ask about anything and I will be glad to help if I can.
Comerc 24 - amazing, beautiful tasting menu. lots of fish,monkfish, sardines, codfish, sea bass, lots more, everything was right on. sleek room - good staff. only one seating, about 50-60 covers. got there at 9:30 and left at 1:00. tasting menus 65 euros or 95.
Tapac24 - great as well. ate there once for lunch and once for dinner. they have the same menu and prices for both . ordered off the specials menu each time. the chocolate desert that is often mentioned on the posts here were at both places. tapas 5 to 8 euroes. plates 14 to 16.
El Quim - in the boqueria. fun little place for a snack. good and lively. only about 15 seats around a counter with 2 guys cooking/waiting. menu on board on wall, so you can point to things or just wing it if you don't know spanish.
cerveseria catalana- went for lunch. real fun place to get down and dirty, fight for a seat at the bar, and eat your heart out, we spent under 35 (for 2 people)euros for a ton of tapas and beer, very good only a notch down from the tapac24, but more challenging to order.
Barceloneta - on the water in the barceloneta section. more old school and traditional but very good. the english menu is easy, unlike many other english menus which don't really help all that much.
el vaso de oro - another informal lively tapas bar reasonably priced. more meat tapas. long bar and only 4 or 5 tables. loud and can spend under 30 euros(for 2 people) and eat and drink alot
La vinya el senyor - wine bar, tapas were very ordinary, sent down by dumwaiter. nice outdoor seating in old barcelona the best part of this place.
cata 181 - small 12 table wine bar with great tapas, asian influences and moderate pricing. communal tables make for fun too.
textile cafe - right across from picasso museum, had lunch 11 euroes 3 courses including wine or beer. more americanized and pretty outside seating.
had drinks at AGUA and CDLC down at the beach. both pretty pretentious bars that were overpriced - more a place be seen and look at the ocean than a great place to eat.
some general info:
crossing the street, be careful, the green man signal(meaning to cross) is short and when the man starts flashing it only lasts 2 seconds before going red, not like NYC where you still get at least 5 to 10. saw 2 accidents.
graffiti - it is everywhere but don't let it be of a concern.
buses and the metro. you can buy 10 trips for 7,70 euros, single rides 1,35 euros. buses will accept cash. took buses far more often because they get you closer to where you want to go. if you are going to parc guell take the 24 bus rather than metro and save yourself alot of walking. metro shuts down reletively early and buses change schedules after like 11:30, so look for the N buses (night) if out late.
taxis - small stickshift cars. 2,25 to start and pretty expensive after that. don't assume the driver knows where they are going, as 2 out of the 3 times we took a cab, they used a map to find places. Commer 24 and Barcelonetta, both common restaraunts they didn't know.
safety - seemed really safe never saw or experienced any trouble, some homeless and people trying to sell you things, but not pushy.
airport - huge, lots of walking. used the aerobus 5 euros from the airport to placa catalyuna where we stayed, they run all day.
have fun if you are going and ask about anything if you want info.
For Comerc24, you will definitely need a reservation. I would call as soon as possible for Friday. Sometimes seats on the counter are available for walk-ins. It is comfortable so if they are full, you might ask if there are space there. It is not like most tapas places where one eat standing up or just a bite a two. One tends to eat a full meal except everything is served in small portions. Don't miss the baby octopus, scallops, foie gras, suquet; for dessert: the fried bread soaked in custard and the chocolate mousse with salt and olive oil. I would avoid anything that has "salad".
we had made reservations well in advance. there were 3 or 4 couples at the bar, and I am not sure if they had a reservation or walked in. we were 45 minutes late and were still seated. now that I think of it, I don't think anyone else came in after us. commerc24 is definetly a special night out, to sit and enjoy - not a tapas bar type place. tapac24 we walked in and they line you up against the wall so there is some order of turn, so you don't have to "fight" for a table. we waited about 20 minutes for dinner and 10 minutes for lunch there. For something still very good but not formal I would recommend tapac24. easy walk from placa catalyuna if you are staying near there.
Thank you for taking the time to write the detail post. A comment about La Vinya del Senyor; I agree their tapas are just ordinary but they have one of the best wine list in Barcelona, amazing for a small wine bar. It really is not a place to eat a lot of food but to nibble and sample their wines,.