Don't make any assumptions about flight prices. You have to check for your exact dates for various destinations. Which places are cheap or expensive to reach changes constantly, and is simply not predictable.
I'll re-post my favorite example: in March 2017, I was looking at flights for May 2017 (so, according to some, too late to get good prices). I found nonstop flights from NYC to Zurich were $349 on a choice of airlines (not a typo - three hundred and forty-nine dollars all in!). I then looked at Geneva. Nonstop flights were about $1200; the cheapest one-stop was about $650 on Royal Air Maroc, with a very long layover in Casablanca (something like 10 hours); and the cheapest one-stop flights with a decent layover were about $700.
Why was Zurich so cheap? Why was Geneva so much more expensive than Zurich? Your guess is as good as mine.
Another example: my sister took her family of four to Prague this summer. Since she was traveling with children, she strongly preferred a nonstop, and from New York there was only one, on Delta, also sold by Air France as a code share. Delta and Air France were charging about $800 per person for this flight, but she was able to get it from Expedia for about $400 per person. So, they flew Delta metal, on an Air France code share, booked through Expedia. It all worked fine, and the savings were worth using a third party booking (meaning she didn't book through the airline itself, as usually recommended). However, they were thinking they could get similar prices next year to Europe - I had to gently explain that $400 per person, in the height of summer, for a flight to Europe, is not something that can be counted on!
If you do fly to Dublin, which can indeed often be a cheap flight, don't forget to add the cost of getting between Dublin and you desired destinations, as well as the cost of hotel in Dublin (hotels there were so shockingly expensive for my potential September 2018 trip that I went to London instead - it was actually cheaper!). Do investigate Royal Air Maroc - sometimes they are cheap, sometimes not.