We booked two rooms for two nights at Rivermere 4 months in advance. Of course, we didn't know that you could basically show up anywhere in Ireland and find a hundreds of B&B's in town that take walk-ins. I guess everybody rents out the rest of their house as a B&B to make ends meet. But I would recommend a reservation in-advance, since you'd be taking your chances on "house-hunting" if you arrive late in the afternoon.
The picture of Rivermere doesn't do it justice. It's an ADORABLE little B&B, less than a mile down the main road to Killarney National Forest and the Muckross House. Definitely walkable if you're planning a late-night pubfest in the bustling, picture-worthy town, but a slightly steep upclimb on the way in. (Worked fine for that night we wanted to inbibe a tad bit too much!) It was on a loud road from 8am to 11pm, but we were able to open the windows wide-open at night and didn't have any trouble with sound sleeping. Beds were very firm, but not so much as to ruin your back.
We got one room with that RARE king-size bed and one with a double and a twin. (Men are too tall for a twin, so they must get a double-size bed for diagonal sleeping).
WARNING: One of the rooms got terrible shower pressure, shutting off several times when we were shampooing! The owner (helpful, if not a tad bit too busybody, and with a voice eerily similar to Mr. Smithers from the Simpsons) seemed genuinely suprised and concerned when we told him about the terrible shower. He said he'd check immediately that one of the pumps had gone out. Might be fixed.
Our only mistake? Staying only two days. This part of the country has so much to do, we should have stayed 3 or 4 nights. Rivermere had the BEST breakfast (included) that we had throughout Ireland. All breakfast in Ireland is the same, but the scrambled eggs were fluffier, better-quality toast, awesome fruit assortment, much better sausage (although still tasted weird, with extra fillers in the meat unlike American sausage) and the RARE cup of good coffee served in a French press. (I'd order tea the whole time in Ireland, the coffee is gross!)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.