Please help me decide best time to visit Sagrada Familia with kids

Although you will be jet lagged, I suggest the afternoon.....maybe around 15:00. The tour groups have timed entrance appointments until around 14:00. The crowds thin out (a bit) after that. Otherwise - the place is packed. Still worth seeing, though - crowded or not.

Monday
•Las Ramblas - La Boqueria, Placa Real
•Bari Gotico - Cathedral
•Passeig de Gracia - Casa Batllo, Casa Mila

Tuesday
•BOOK a first up visit to Sagrada Familia

Aim for these logistics, with quite generous timings.
08:00 Checkout of hotel, storing luggage
08:30 FGC & Metro to Sagrada Familia
09:30 Book entry to SF
12:00 Depart SF by Metro & FGC to Hotel
13:00 Retrieve luggage
13:15 Book taxi
14:00 Arrive at port to board your ship

Ildefons Cerda is technically not a metro station, it’s on the FGC line, but yes, think of it as a metro station. I do, for it’s my station when I’m in town.

Barcelona transport can be confusing, as you have 3 types of commuter trains.
1. Metro - which are run by TMB. Look for the symbol of an M in a diamond. Lines numbered 1-5 & 9-11.
2. Ferrocarrils de la Generalitat de Catalunya (FGC) - which are the city trains run by the state government. These are shown as dark blue on the metro map. Look for the symbol that looks like 2 links of a chain. Lines numbered 6-8.
3. Rodalies - which are the inter urban trains run by the national railway renfe. Line numbers prefixed with an ‘R’.
http://www.renfe.com/viajeros/cercanias/planos/barcelona.png

Thanks, @djp_syd - that was very helpful. You're right, now that I look at it, Ildefons Cerda is the two-link-chains line, but am I correct in thinking that I can get on that train, and then transfer to the "real" Metro lines at Espanya or similar?

Also, I have found evidence that Sagrada Familia does indeed have lockers since you are not allowed to take items up in the elevator. My question is, would those lockers accommodate carry-on sized rolling luggage? Would we even be allowed to take such luggage inside? All references I can find to the lockers say they're for "large bags or backpacks."

I don't think the lockers at Sagrada Familia are any where near large enough for carryon size luggage. I stored my daypack in one this January and while it wasn't a tight fit it wasn't exactly rolling around in there either.

Thank you, @jen - glad to hear a firsthand confirmation. That was what I had suspected, and I'm really glad to hear it confirmed by a real person with real experience! Love this board!

Yes, you are correct in thinking that you can get on a train at Ildefons Cerda, and then transfer to the "real" Metro lines at Espanya, though it’s a bit of a walk.

For example, for the approx 30 min journey to Sagrada Familia ...
•Line 8 (FGC) from Ildefons Cerda, direction Espanya, to Espanya.
•Line 1 (red) from Espanya, direction Fondo, to Universitat
•Line 2 (purple) from Universitat, direction Badalona, to Sagrada Familia

Ticketing is integrated between the 2 systems within the city area, so transferring is seamless on single tickets or T-10 card, for example.

@fredandkell... if "another real person with real experience" can be of help... yes, there are lockers at Sagrada Família but these are, like in most other museums in the city, only big enough to store a backpack or similar. Think of a supermarket locker type.

For info, visiting Barcelona's attractions with a carry-on suitcase it's rather complicated since, other than one's own hotel, there are few places that offer luggage storage --less than a dozen in all the city as far as I know. Only a few museums, really few, come to mind where you can store anything as big as a carry-on. I would imagine the events in the recent years across the world regarding terrorism didn't help either.

I believe this is what we are going to do.

Monday - head to hotel via taxi. If we can check in early, nap. If not, drop bags and taxi to Placa Catalunya and do Ramblas walk, Barri Gotic walk, and Casa Mila exterior, using Metro T10 ticket to backtrack between walks, and depending on how grouchy/tired kids get. Taxi back to hotel.

Tuesday - taxi to baggage storage 200m from Sagrada Familia (using bagbnb.com). Timed ticket at 10am, spend 2 hours here (or until kids get bored), pick up baggage, taxi to cruise terminal.

Thanks again to everyone for helping me "talk it out" and organize all the thoughts banging around in my head regarding logistics! Again, if it was just me and the husband, it would be easy, but with two kiddos traveling to Europe for the first time, I'm going for seamless/convenience!