Last Minute Plans. Please Help!

I haven't done Mizen Head so I can't comment on that, but I drove the Beara Peninsula in a few hours; I could have spent longer, but that's what I had available. Be advised that there are some very narrow roads on that peninsula - that's why the tour buses don't go there. That was my scariest day of Irish driving in two weeks, and if I had it to do over I'm not sure I would. The views were beautiful, and the remoteness made it special, but Slea Head Drive in Dingle was just as beautiful with better roads.

For me, this would be too much ground to cover, and also not enough time in the towns and cities, but I assume from your plan that you prefer natural sights and countryside to towns. You're also changing locations a lot, but you've built in some two-night stays, and your plan gives you the chance to sample different towns each evening (since you'll be busy all day most days). But do be aware that you will be spending a lot of time in your car, probably more than you think.

Howth is nice, but if it were me I'd spend that first afternoon in Dublin. There's plenty to see that you won't have time for when you go back at the end of the trip. Again, though, it depends on your priorities.

Have a wonderful trip!

Looks like a pretty well organized itinerary to me. You've obviously done some extensive research and identified some of the best off-the-beaten-path side trips in the west of Ireland.
To answer your specific questions: 1. Staying in Glengariff would put you about 20 minutes closer to your Day 3 drive out along the Beara peninsula which will keep you busy for most of a day, especially if you drive out to the Dursey Island cable car at the end of the road. With 6 of you it probably wouldn't be timely for everyone to cross over to the island (it only takes 3 people at a time) but the view is spectacular and the drive to it is beautiful. The road is indeed quite narrow, but can be negotiated easily enough if you just stay alert for approaching traffic and get comfortable with using the pullouts.
2. Mizen Head is nice enough but would probably be too much driving for one day. Personally, I'd stick to the Beara peninsula.
3. With an early start you can easily cover your day 5 itinerary, especially if you concentrate on the northern half of the ROK and the Skellig Ring Road. I wouldn't necessarily feel obligated to drive the entire ROK loop. The southern part is nice enough, but I think you'll get the general idea if you stick to the northern half. Do try to carve out a few hours at the Gap of Dunloe - the walk up the Glen is one of the prettiest in Ireland, and the jaunting cars are a lot of fun.
May is a pretty good month to visit Ireland. It'll be shoulder season - ahead of the big tourist crush that starts when schools let out in June so not as crowded and usually blessed with decent weather. You're still likely to encounter one or two rainy days, however, so plan (and pack) accordingly.

Thank you Melissa and Robert for your swift replies. Mellissa , you are right. I'm a nature lover and I prefer village to city. In fact , I fall in love with the images of villages in Ireland.
One thing that I concerned is the narrow roads in Ireland. Will it OK to drive a mini van in Beara Peninsula ? Will it be too narrow for a mini van ? Another thing is I don't want to spend my holidays mostly in a car or rushing from one point to another. If you will going to plan , what places of interest will you choose and what will you leave out? How are you going to divide the limited nights that i have? Experienced and knowledgeable travellers out there. Please speak out...

You might want to take a look at the street view feature on Google maps and preview some of the rural roads you're considering. It provides a good "driver's eye view" of what you'll be getting into on some of the narrow lanes. In particular, take a look at the R572 out to the end of the Bear peninsula...it's pretty typical of what I'm talking about. Then decide what your comfort level will be. Per Melissa, many of the country roads in Ireland are quite narrow - only one lane wide in many cases, ie not wide enough for two cars (of any size) to pass side by side. The local rule is that one of the approaching drivers must pull into one of the pullouts provided and then wave the other thru. It really isn't that big a deal...the locals deal with it every day without too much drama. I can tell you from personal experience, however, that it's a situation guaranteed to make your heart rate spike the first few times you encounter it.
If you're comfortable with driving on the left then the rural roads shouldn't be too much of an issue. It's where the pretty rural scenery that really defines Ireland is located after all. If, on the other hand, you determine that it's just not for you then I agree that maybe you're better advised sticking to places like the Dingle peninsula which aren't quite as nerve racking as the narrow lanes.

Thank you Robert for your valuable advice. I think we will go ahead as we used to drive on the left. Really looking forward for the trip and witness the beauty of the Ireland. Thank you again ...