Ohio to Barcelona to Paris

Not sure what airline you are planning on using due to Port Columbus not being very international, but I have found Air Canada to be the best way to get to Europe and back from Columbus. Short hop to Toronto, then on to Europe. Look into booking an open jaw flight, arrive in one city, depart from a different one.

You may find cheaper flights with Air Transat as they fly Toronto to Paris & Barcelona. (Prices in Canadian dollars).https://www.airtransat.com

A good advice site for European rail travel is:>http://www.seat61.com

Julie, do you mean that you are buying one-way tickets when you say you will plan your return flight in Paris? I think a multi-city roundtrip would be cheaper; sorry if I misunderstood your post.

Hi Julie, I just started tracking airfare for May and I'm looking at Delta out of Detroit and possibly Air Canada. You have to do some experimenting with the airline websites to figure out the best/cheapest days to fly. If you indicate that your dates are "flexible", you should get some options. With your itinerary, I'd suggest flying from Barcelona to Paris unless there's some reason you want to do the long train ride. Hope you have a great trip!

Do you intend to fly to Detroit and connect to Air Canada, or drive? If it is by car, you might consider continuing on a few miles across the Canadian border at Windsor to catch the Air Canada Windsor-Toronto service. Unfortunately there is no non-stop service between Toronto and Barcelona. AC does have a daily non-stop Toronto-Paris.
While Air Transat can be a bargain for passengers originating in Toronto, it is a charter airline which complicates transfers to other carriers. I expect that you would not be able to check your luggage through to Europe and probably would have to go through more complicated immigration and security procedures than with Air Canada (or Air France which also flies Toronto-Paris.)
The simplest answer for minimizing ticket prices is to fly a month later, at the end of September, when the summer peak fares begin to decline. Or did this year, at least.

The Barcelona-Paris TGV train takes 6.5 hours and the cheapest tickets go on sale about 3 months in advance of your travel date. However, flight prices can be very competitive on Easy Jet or similar carriers; see www.skyscanner.com.

Apologies if you know this already, but you want to book your flight as "multi city" (into Barcelona and out of Paris, all on one ticket). Don't book two one-way flights, as that's much more expensive.

As for days and times that are cheaper, it varies. Usually flights on weekends cost more. And august can be more expensive than September. But you just have to keep checking, and when you find the flights you can afford that work for you, book them and don't look back.