Suggestions for arriving at 6am and check-in is 4pm

Change hotels entirely if your room already booked is refundable?

If you cannot change your hotel.... it may not be that bad. You actually won't be awake for 28+ hours: PDX to east coast is roughly 5 hours, then the flying time from JFK to Barcelona is about 7.5 hours. You may catch an hour or two of sleep on the flight. Yes, you will be jet lagged, but it's true, if you get out and walk, you can do it. You wisely have already found out you can drop your bags at the hotel. Then you can ask them for a nice breakfast recommendation, and linger over coffee and pastries. Afterwards you can find a park or public place to people watch until 4 pm (and they may actually let you check in early if you schmooze them right...)
Have a wonderful adventure!

I have inquired at the Hostal Oliva if there was a room available, but due to room departure times, it had to be the same room we have reserved to be able to stay there for more than 2 hours.

I didn’t fully understand the above statement but interpreted it as you won’t be able to get into a room at 6am, but you might get in earlier than 4pm. Hotels will often let you into the room after the previous guest has checked out and housekeeping has made up the room. That could be in the early afternoon.

I hate the first day after an international flight and I can’t sleep on planes. Here are some things I’d suggest. I skip the breakfast on the flight; it isn’t worth eating. I drop off my luggage at the hotel and ask if there is any possibility to check in early; sometimes the hotel will prioritize getting your room made up early. I go to a restaurant or an outdoor cafe and have a leisurely breakfast. I try to take a leisurely walk outdoors; parks are good and you can take breaks on the benches.

The other thing you can do is book your hotel room for the night before your arrival.

Let' say your plane leaves PDX on Wednesday morning and you arrive Thursday morning.

Book a room in your hotel for Wednesday night. This way, when you arrive at around 7-8 AM you can go directly to your room.

Makes sure the hotel is aware of the fact that you will be arriving in the morning and not to put you as a no-show.

Thanks for the ideas. For clarity, I have tried to book the same room, but it is taken. The trip starts in less than 3 weeks, so too close to find a good hotel like the one I found recommended in Rick Steves. I think we will have to follow the breakfast, bench, and beg politely option and hope they can accommodate an earlier check in time. Lesson learned to book a room for the night before.

Molly

I finally found the perfect answer after trying a few of the forum suggestions; there weren't any hotels available this close to our trip that didn't cost a fortune, etc.

I now have a 4 star room from 11-5pm/17:00 within walking distance of our booked hotel in Barcelona. It costs $81, is cancellable until the last moment, the cost includes tax, etc. We don't plan on sleeping the whole time, but it will give us a place to rest, shower, and escape for a while. I anticipate a much smoother start to our trip; a nice stroll in the neighborhood and ordering dinner, when I can actually read the menu, before we turn in that night.

Dayuse Hotels in Barcelona • Hotels by the hour | Dayuse.com

This "broker" site is not limited to Barcelona.

Hope this information helps you get off to a good start, especially if you fly economy from the west coast.

Molly