We used Irish Day Tours for four private day tours and also did the Gravedigger tour. 1) Request Caroline! She is probably the best guide I have ever had for any tour in any country. She was awesome with great insight, stories, history, themed music, and the best personality. Anyone can drive you to these locations but the guide can make it the best experience and she did that for our group. She was extremely accommodating and even altered the tour a little to meet the wants of our group. Sadly, we only had her for one tour to Belfast and the Giants Causeway. 2) Another good guide was David. We had him for the Cliffs of Moher tour. My group were all college-age students and he was perfect for them. Took us to off the beaten path sites, had great music, really engaging with the students, and a very impressive yet exciting driver. 3) The gravedigger tour was one the funniest experiences of the trip. It will make you laugh the entire night while also giving you a lot of historical information. The guides are professional actors and were great to talk to when in character and when they were out of character. There was a lot of swearing and I mean a lot. Even still it was a fantastic night! 4) Boynne Valley Celtic tour was a great easy-going and simple tour. Matt our guide was great for the on-site history at Hill of Tara. The actual bus ride could have been better. I would suggest bringing ear phones and a good audio book or your own music. The actual sites though, were awesome and it was exactly how you picture Ireland. I am not sure if this is the only tour company to do this tour but we had every site, except Trim castle, to ourselves. It was great! 5) The buses were hit and miss and we had every possible option from the best with leather seats, wifi, and USB ports for charging cameras and phones to older buses with just seats and that was it. Needless to say most of our phones died on the latter before the tour was finished. You can try and request certain buses.
I would highly recommend using this company as I will be using them again when I return with another group of students or with just my family and friends. Great company and experiences!