Where to park a car during 3 nights in Barcelona?

You are better off turning in the rental car when you arrive in Barcelona. Rent another car three days later when you depart.

You’ll find a lot of options at www.Parclick.com. You may need to reserve in advance.

Drive to Zaragoza, return the car and take the train to Barcelona. Then take the train to Valencia and rent a new car there.

Badger is exactly right. That's what I would recommend. There is a high speed train from Zaragoza to Barcelona the AVE, and there's another high speed train from Barcelona to Valencia the Euromed.

If you didn’t want to drop off, then pick up a different rental car, consider a hotel with its own parking garage outside the city center that’s on a transit line. Expect parking to cost €20-€25 per night.

I think I'll price out both options. Right now, I'm picking up and returning in Toledo.

I rented a car last trip in Venice and parked it five days in Rome because it was an amazing price for the rental. This trip the price is nothing special so turning it in and picking up something from Valencia back to Toledo (at the end of the trip) may make more sense. If not, I may pick a hotel that's easy to drive to and park near it then take the metro for touring.

Last time we lodged in the Gothic quarter, which was nice, but the area seems to be getting less appealing (both more crowded and more crime).

Thanks,

You don't mention anything about your itinerary, but what you've mentioned so far is major cities (apart from Olite) and having a car in a major city is a major headache. Rent a car where there is an advantage in doing so and travel from city to city by train. The Spanish high speed train will save you a lot of time compared to driving.

I am with @geovagriffith here.

But if you can't do that, let me know exactly where are you staying... then I can meaningfully suggest something :)

Thanks,

Itinerary through Barcelona from memory (First week is Semana Santa) - Day one, arrive in Madrid, train or bus to Toledo (stay two nights Toledo). Pick up rental car in Toledo. Drive to Zamora with a day stop in Salamanca (two nights Zamora). Drive to Valadolid with stops and or day trips to Leon and Medina del Campo (two nights Valladolid), drive to Olite (one night in Olite), drive to Barcelona...

Afterwards Velencia, a southern swing including Granada, Ronda, Antequera, Tarifa, Gibraltar, Baelo Claudia ruins, Costa del la Luz, Jerez, Sevilla, Cordoba, then back to Madrid for the flight home.

Factors to consider:
Four people in car (all with small carry-on bags)
Don't like reserving ahead for transportation or lodging, etc. Prefer to book as we go (major exceptions seem to be Alhambra and, now, Alcazar/Cathedral in Sevilla - any others that must be booked ahead in April?).

Such a large area and so many places you could stop.

Zamora is a nice mid-sized town that can be seen in a day. We stayed the the Parador there. León is very much worth visiting and we stayed at the Parador there too. Between Zamora and León there is a nice castle a short distance off the main road in Valencia de Don Juan. Castle La Mota in Medina Del Campo has a very impressive exterior.

After leaving Valladolid heading to Olite you’ll pass Peñafiel Castle. It too is impressive from a distance. It contains a wine museum. A town that we enjoyed walking around along the route to Olite is Burgo de Osma. Continuing along that route you’ll pass by Ágreda. If you’re religious you could stop at Monasterio de la Inmaculada Concepción to see the tomb of María Jesús de Ágreda, the Blue nun. It is said she was capable of bilocation. Near there is Trazmos, the town of witches and the only town ever excommunicated. In Olite the main attraction is the Royal Palace of Olite. While mostly a reconstruction, it was done well and worth visiting. In Olite we stayed at the Parador.

Thanks,

The two nights in Zamora are directly related to Semana Santa. I liked Zamora last time I was there but would have probably skipped it if not for the Easter Week celebrations. I'm thinking we'll do one day trip from there (and likely another from Valladolid) but be there in the evenings for the processions.