Camping in Wales (Snowdonia)

Our main holiday next year will involve us being all 'outdoors' and doing stuff in boats and on mountain trails and that. The thing is, to keep everyone happy I need certain requirements that will help ensure two teenagers (13 and 16) don't have a meltdown on day one. So if anybody's got any experience of sites that take dogs, have electric hook-up and a wi-fi connection (I know - a wi-fi connection while you're camping ffs) it would be greatly appreciated if you were able to share that information. Thanking you in advance.

Try Shell Island, a couple of miles south of Harlech. Never been myself but know quite a few that have, and everyone has enthused about the place.