Unfortunately, the railway network doesn’t extend to Donegal or Fermanagh so you’ll have to find another way of getting back from Glencolumbkille. The nearest trains are in Sligo and Derry - you might well be knackered by the time you get to Glencolumbkille but covering the Donegal coast on the way to Derry would be well worth it.
When you get to Glencolumbkille, climb Slieve League and you’ll be rewarded by a vertigo inducing view from the highest sea cliffs in Europe. They are three times higher than the Cliffs of Moher and refreshingly tourist-free. Walk along one man’s pass and bring an extra pair of boxers;). Have a pint in the Rusty Mackerel if it’s open. I was there in April and they still had the Christmas tree up. Go to Rossnowlagh and check out Ireland’s surfing fraternity and don’t miss Smuggler’s Cove which is one of the best pubs in the entire country. Rossnowlagh is also the site of the only significant orange march in the south. It will probably be over by the time you get there but I just thought you’d like to know.
In Fermanagh, head to Lough Navar and gaze over the lakes from the promontery. Go to the Marble Arch caves, which are pretty cool and get langered in Blake’s in Enniskillen. Take on the locals at pool in the back room and enjoy the bonus of having the ladies jacks right beside the pool table;).
You’ll have to take the ferry from Tarbert in North Kerry to Killimer in Clare if you want to avoid Limerick City (and trust me, you do). My wife is from Tarbert and her Da has a pub called Carmody’s. I’ll be there for some of July so call in and ask for Phil - if I’m there, I’ll give you a tour of lesser known North Kerry and you can leave the bike behind for a day.
Inishmore is great but if you decide to venture deeper into Donegal, take the ferry to Tory Island. It makes Inishmore look like downtown Manhattan.
Try to co-ordinate your trip to Galway with the Galway Races, although accommodation will be a major problem. The city just goes mental for the week: I guarantee you that you’ve never seen anything like it.
When going from Clifden to Westport, take the Doolough Pass - it’s fantastic. If you have the time, climb Mweelrea (Connaught’s highest mountain) and look over Killary Harbour, which is Ireland’s only fjord. If you’re not sick of mountains by then, go up Croagh Patrick on the coast road to Westport. Make sure to pray to your god in the church at the top. Actually, Reek Sunday is in July so you might get to see one of the weirdest pilgrimages ever. Lots of god-botherers climb the mountain and say decades of the rosary etc. It’s bare feet and broken ankles all the way so have fun.
The downside of Ireland is that it’s expensive, especially with the weak dollar. The good thing is that there’s loads you can do for free (including cycling, obviously). Make the effort to climb mountains and get the hell away from the tourist traps (and, God knows, with places like Dingle, Clifden and Doolin on the list, you’ll have no shortage of them).
We’re the nosiest crowd of bastards you’ll ever meet so take advantage of our natural curiousity. Talk to old men in pubs and avail of diplomatic immunity to ask stupid questions.
Swim a lot. The water is a bit cold but you’ll be near some of the best beaches in the world. If you can manage it, don’t miss Inch strand on the Dingle Peninsula, Ballybunion for a bit of bucket and spade and chips in a plastic carton, Spanish Point and Doonbeg in Clare and Magharoarty in Donegal.
You won’t be short of music but most of it will be shite. For the best of it, go to Slieve Luachra on the Cork/Kerry border and West Clare. You’ll get the usual diet of big city art museums in Dublin but IMO, that’s not really what Ireland’s about. Someone else might help you there. For literature, the best thing you can do is to get your holiday reading together. Try everything from Joyce to Roddy Doyle. There are obvious literary Meccas - the Joyce Tower in Sandycove, Coole Park, Listowel etc. etc. - but it’s all a bit marketed and your better off reading something you love in a place that makes it mean more than it would do otherwise.
Hurling. You probably won’t get to a match but watch it on television and fall in love.
And, finally, my advice to all holiday makers is to be a child again. Nobody knows you so do the things you always wanted to do. Swim in your nip, sing silly songs in high places, slide down hills on your arse, get embarrassingly drunk, make inappropriate ovations to women who are out of your league and laugh your hole off on a regular basis. And don’t plan too much. Just get on your bike and see what happens.