Generally I go for a day trip (I live 1 1/2 hours away by bus), and when I have stayed there it’s been as part of groundwork.ie, a conservation project that means you stay in the ground of Muckross House which the public can’t do.

There are TONS of B&Bs and hostels around Killarney, even some by the lakes and national park that are only a walk (or a quick bike ride) away from places like Torc Waterfall and some of the historic settlements around Killarney.

http://www.corkkerry.ie/ has lots of pages about different types of accomadation and what they’ve been rated, and things to do and how to get there. Good luck! If you need any more help, feel free to ask.