It's a superb area isn't it? I've not actually walked any of the Glyderau east of Y Garn, as I find the scrambling in the central region too tempting - can't bring myself to plod up Elidir Fawr, for instance, when I can do Bristly Ridge instead. I find Y Garn a really underappreciated summit - perhaps the best view of the range? Very handsome mountain too.
Cwm Idwal on a quiet evening is just heaven.