If you start from Rhydd Ddu you can continue straight on at SH582524, and on reaching the col below Yr Aran ascend Snowdon by its south ridge. It is a nice route with one short section of easy scrambling. Descend by the regular path.
I once lingered on the summit till sunset and then followed the path from SH575553 in the dark. It took a while to navigate and by the time I got back to my car it was too late for a curry from Penrhyndeudraeth. That was overdoing it, but I do recommend the sunset.
Thanks for the info but as I'm not too familiar with this side, I'll stick with my planned route. Checked the cost of the train ride today between Snowdon Ranger and Rhyd Ddu; its £2.70 one way.
Thanks nltom for the suggestion. This would probably shorten my route and make a nice start to the day. http://www.festrail.co.uk/fares.htm doesn't give a ticket price for the ride between the two stations. Is it possible to buy a ticket to cover this short journey and at what cost?