In the last few years, there's been a big investment of time and money in opening up off-road walking routes all over Ireland.
I've tried a couple of them and they were good.
The Discover Ireland site has maps and directions for loop walks and forest walks. I'm not sure if beach walks are covered.
The site is good, but it doesn't give any opportunity for feedback on the routes. This thread could be used for posting experiences of these routes and any particular pleasures and pains associated with them.