On our first day next Sunday we will be traveling to Dingle. Since it's the day after flying (from JFK) would you suggest taking the N18-N20-N21 route through Limerick and Tralee or the N68-N69 route through Kilrush and Tralee?
I would say it depends on what time you are leaving Shannon. If it will put you in Limerick at rush hour that could mean a 1 - 1/12 hour delay just getting through the city. Going through Limerick and taking the main roads south is usually the quickest route. Also, you do not need to deal with as many small roads.
On the other hand, if you take the highway toward Ennis you will have to get off well before Ennis as there is no exit there presently. If you miss the exit you could end up well past Ennis. Then you will need to take smaller rural routes to the ferry. Depending on when you arrive in Killimer, you may have a wait for the ferry.
I suppose there are pros and cons of each route. Sorry there is no definitive answer.
I realized there's not an easy answer! We arrive on Sunday morning at 9:05, so hopefully we'll be on the road by late morning. I don't expect Limerick traffic to be a big issue. I'm also not planning on rushing to Dingle, but the idea of taking thr "roads of least resistance" is appealing.
I'm leaning towards the Limerick route at this point.
I obviously did not read your first post right. Since it is a Sunday morning you will have very light traffic through Limerick. I would go that way. There are multiple roundabouts approaching the city. Follow the Cork road at first, till you see signs branching off to Adare and Tralee. Once out of Limerick it should be smooth sailing.