Travel from US to Ireland and France

We have booked Easy jet several times from US and not sure if it is cheaper to book once in Europe but you may not have as much choice if you wait until in Ireland. I suggest you fly from US to Paris then Ryanair or such to Ireland and home from.Ireland or the other way around. When book flights book multi City also called open jaw. It would save you time not flying back and forth to Ireland. When you leave from Ireland home to US be sure to allow three hours at airport as you do US pre clearance there and arrive in US as if on a domestic flight.

Booking short flights within Europe is easy and cheap. The biggest challenge will be prioritizing and sorting out what you want most and picking from your available options.

I'd focus primarily (and first) on the flights to/from Europe (flights from North America to Shannon are quite limited). before booking those, look at your options for getting between Ireland and Paris, but them together and there you go.

Use Google Flights and Skyscanner (or similar site) to research the flight options between Shannon or Dublin and Paris that's best for you. Then book that flight directly with the airlines (don't use third-party booking sites to actually book the tickets, but do use them to find all the options, so you can pick what you want).

All other things being equal, you will pay more for flights back to North America departing from Paris than you will on flights back to North America departing from Ireland (because of fees - airport fees in Ireland tend to be low). That may or may not help you choose what order to do things in.

If it were me, I'd go do the west of Ireland first (it will require more energy from you), I'd end the Ireland portion of my trip in Dublin, then fly to Paris and relax there - but there are plenty of ways to slice this depending on your priorities and travel tastes/style.

Just be aware that options for Shannon will be thinnest (most folks fly in to/out of Dublin because there are so many more choices there).

Hope that helps a bit

www.Skyscanner.com

I’ve heard it’s much cheaper to book local airlines within Europe

I've never heard that. IME booking "local" airlines is just as cheap or expensive anyplace you have a working internet connection - I've never heard of prices differing for locals.*

What I do know is that booking flights (or trains or lots of things) at the last minute is usually more expensive than doing so far in advance. The business models of most European airlines (and in fact most airlines anywhere) is that the cheapest seats are offered far in advance, they get snapped up early, and as the date of the flight approaches, prices go up, sometimes way up. If you wait until you are already in Europe to buy flights, you will almost certainly pay more (perhaps a lot more) for the same seats you could buy now (and that some others have been buying since around last October at the lowest prices). Flights do sell out, especially in popular places in high season. If you're counting on a flight to get you from Point A to Point B, you are gambling that they'll still be available when you get around to booking them.

Also not to be ignored: How do you want to be spending your time in Europe? Relaxing with a pint and some fish 'n chips/a glass of wine and some pasta/whatever, or trying to figure out how to buy tickets on your phone with perhaps sketchy connectivity?

I like certainty and prefer to complete all needed tasks as soon as I can, but others have different ways. Unless you have some significant uncertainty built-in to your plans, I don't see any benefit in waiting until the (relative) last minute to book flights. I get nervous when important tasks don't have a big green checkmark in my plan...

 * There's one exception: some airlines do have different prices when you book on the US version of their website versus the domestic/national website that residents would use (I've seen this in South America, where flights to say Easter Island or the Galapgos may be substantially cheaper when booked from Chile or Ecuador websites respectively; Americans pay more booking via the US version of the website). But that is a relatively unusual practice in a very different market (airline monopolies and no competition); I've never seen or heard about such distinctions in Europe. The airline model for European airlines are hyper-competitive, everything is all about cheap, cheap, cheap, the lowest prices - and there's little interest in where you come from. Prices are low to begin with and they don't change appreciably based on which version of their website you hit. In short, location is a non-issue. Timing – the proximity to the actual flight – is often (usually) a big issue.

If you wanted to do Paris first you could open jaw to Paris out/Dublin return.

Then book Aer Lingus Paris to Shannon or even Air France Paris to Cork.

The #51 bus from Galway to Shannon extends to Cork hourly.

But City link also run a bus every 90 minutes or so direct from Cork Airport to Limerick (for Ennis for the tour start)