Welcome to Michele's Forum!   

My brief take on your plan is that it is do-able, if a bit frenetic.   Although it is NOT my preferred travel style, what you have proposed is actually much more reasonable than most typical First Timer's.  The trick will be in the execution -- you will be passing by / near SO many sites that the temptation to 'Add Them In' will be quite strong.  For that reason, I would strongly suggest adding one more night to Galway, or considering a flight from Shannon to London, in order to not 'short-change Galway / Clare as much.

For example -- The drive from Dublin to Killarney will likely take between 4 - 6 hours of DRIVE Time -- depending upon route, traffic and weather.  The shortest and quickest route is via Limerick and Adare.  You could also opt for the slightly longer choice via Cashel and Mallow, or the even longer trip via Cashel, Cork (Blarney) and Macroom. 

In any event, after picking up the car and heading out on ANY of those routes, you can expect to spend the better part of the day just GETTING to Killarney -- if touring some sites along the way is your goal.  Otherwise, you MIGHT be better off taking the train to Killarney and renting a car from there, just to get a 'jump' on the Killarney area attractions.

A final alternative would be to Bus / Train to Galway on Arrival Day rent a car there on Day 2 and REVERSE your plans direction, to end in Dublin the day / night prior to a flight or ferry to London.

I'm sure others will chime in shortly with their comments / suggestions, too!  Happy planning!          

Judy has made an excellent point about the Ring of Kerry.  Many people feel that the 'Best Bits' of the Ring is the N71 stretch from Kenmare to Killarney (and possibly, as far as Killorglin).  I don't know if I would go quite so far, but a LOT depends on the time of year, weather on the day and which Ring of Kerry route you follow.

The basic, Tour Bus Route takes about 6 hours to drive, with one or two stops along the way.  The 'Grand Tour' route, which includes Valentia Island and the Skellig Ring will add another 2-4 hours, depending upon stops.  In either case, there are numerous potential 'detours' along the way -- Kerry Bog Village, Rossbeigh Strand, Cahergal, Leacarabuaile and Staige Ring Forts, Ballycarbery Castle . . . the list goes on and on . . . and doesn't even TOUCH on the delights in and around Killarney.

Since you can't possibly 'see it all', Judy's suggestion might give you the best of BOTH worlds -- given your limited time.

The open jaw Ireland idea works with only 3 days but I would be coming into Dublin and out from Cork for London ~(Heathrow) rather than Kerry to Stansted or worse Luton. Rail and Sail from Dublin to London Euston is a 9 hour journey minimum but if you do prefer that option stick with Stena Line over Irish ferries and keep your Dublin time to the end rather than 2 hits front and back, There are express bus's from Dublin airport to several Irish destinations including Galway and Cork.

Thank you all so much for your advice! I agree, it does make more sense to skip ROK in favor of Dingle. The areas around Killarney you described are what we were mostly interested in seeing anyway! My mom and I came to the decision to fly to London from Dublin when we realized how long the ferry/train would take. I hadn't even thought of flying out of Cork but I will look into it! I'm sure I will be posting more questions once we start narrowing down our itinerary! This forum has already been a great help!

Christina

After a lot more planning and thanks to everyone's awesome advice, I have changed up my original itinerary to maybe something more doable. Again, any input is welcomed!

Day 1: Fly into Dublin arriving early. Hop on/off bus tour
Day 2: Rent car in Dublin early and drive to Galway. After a few hours to check into B&B, have lunch, etc., we would drive out to see the Cliffs of Moher. I'm a hobby photographer and after looking into it I think seeing the Cliffs before/during sunset would be best. Sunset is around 9pm in May, so I'm thinking getting there around 7 would give us time to walk around and get lots of photos.

Day 3: I have two options for this day, both end with staying the night in Galway.
Option 1: Drive the Connemara Loop with priority being the Sky Road out of Clifden and Kylemore Abbey. I realize this makes for a long day of driving but I'm hoping it's still doable!
Option2: Take the ferry out to the Aran Islands (Inishmore) and explore for the day

Day 4: Drive from Galway to Dingle stopping wherever we want for food/photos. Stay the night in Dingle
Day 5: Drive the Dingle Peninsula and continue on to Killarney. Stay the night in Killarney.
Day 6: Killarney National Park (Muckross House, Ross Castle, Torc Waterfall) Stay the night in Killarney.
Day 7: Drop off the car and take the train to Dublin for our flight to London. Or drop off the car and get a flight out of Kerry or Cork. (I haven't had a chance to look into these flights yet)

I have also just ordered Michele's book and I'm so looking forward to getting it! Seems like a great help with planning out the details!