If you ever get the chance, GO! Your options are like a list you can only dream about, but just let yourself be taken where the mood takes you, try to avoid shedules. Ireland is that sort of Country.
As for getting there, you arrive however you like, whether on a Cruise Ship, a Ferry, by Plane, it matters not. Even when you set foot on the Emerald Isle, you have so many ways to travel. You can drive, on very old roads, virtually no Motorways, leisurely cruising through ancient Villages & Towns, with multi-coloured houses & Inns. You could go by Bus, meaning there is more scenery for you to see, you can even rent a Horse drawn Caravan! You could take the Train, but you really will miss out on some wonderful views, and won't be able to just stop a while.
I would recommend talking to the Locals as soon as you can, they are a very interesting People. You will of course have to take most of what they say with a pinch of salt, as the Blarney flows freely. You have to sample the Genuine Guinness of course, you can even take the Breqwery tour, although I would not waste too much time in places like Dublin. There is nothing wrong with the big places of course, but you will enjoy the experience more if you get out into the "Real" Ireland.
When you enter an old Pub, and you will, you are taken back a lot of years, and the general ambience is very true, not staged at all. You will find plenty of Live Music played, most of it very informally. I was watching a group of Musicians playing away merrily, when one of them simply got up and left, this seemed strange to me, and I did ask someone why he had gone. I was given my answer - "He has gone because he is not there any more" - fair enough, it did not matter. Much later, he did actually return, and simply dropped into another seat in the middle of a tune and carried on as if he had just been to the Bar! You are getting to understand the Locals now.
If you like scenery, you are in for a treat, the coastline is as rough and craggy as the come, with some remote beaches. Some beaches have a Pub & a couple of Houses nearby, but please do not enter a Pub without your shirt, this is bad form. There are some very secluded bays, where you will not see a soul for hours. You can see Harbours, and fresh fish being landed daily, I was even treated to a wonderful spectacle during my visit. The Seals all get together twice a year, and form up a few miles out to sea, then they "Herd" all the Mackerel towards the Harbour, and the water boils with thousands of fish! This is a very special sight, and the Seals get as much as they can eat, the Locals help themselves to the Fish by the Bucketload, everyone is a winner as they say.
There is a lot of Religion in Ireland, and you will see some wonderful Churches. I went in one, which was fitted with a coin-operated electric candle machine! This would have been state of the art in the Fifties, all in Copper & Brass, you simply drop in a coin, and press a button to switch on the "Candle" of your choice.
Crime is very low in Ireland, People leave their doors unlocked, and you often see cars parked up, securely locked, but because it is warm they have left the windows open! This is a very nice sight. The younger element have a sense of respect for their elders, and they will often step into the road to allow older people to pass, very nice too.
Well, I have hopefully given you just a taste of Ireland, please make the effort to get there before you live to regret it. Thank you.