You can always do it on your own. I personally enjoyed Blarney. I expected a basic tower house and was pleasantly surprised that there is a castle ruin, cave, dolman, park, estate and woolen mill. Really more to see than I was expecting.
I have taken some tours through Bus Eiren. Just day tours but I've found them to be a good value.
I've also had pretty good luck using my Amex card for CDW insurance. I had years of rentals with no damage so was more than happy using the card's insurance. I pay a one-time charge of $25 for the whole rental, so saves quite a bit. This June I had my first accident. It was minor but about 2700 euros damage. It took some effort to gather the information they wanted for the claim and make sure it was received by them (maybe a hour of work, three times) but once that was accomplished, they paid the claim.
I haven't used it in Ireland yet. I'm going in May. It's not on every Amex card. I used to have it on my Costco card. When they went to Citi, I got an "everyday cash card" just so I could continue the CDW offer. Some countries are excluded. It also has different rules by states, and some states don't allow it, because it's an insurance product. If you can take advantage of it, it can be a big money saver.