From the tourist office I got the timetable for the local buses leaving Caernarfon, which was good to have as I was making daytrips to other places in northern Wales. Buses in Caernarfon all leave from Penllyn in the town centre.
Buses to Llanberies leave Caernarfon about every half an hour during Monday - Saturday, and less frequent on Sundays. Some of these buses go to Victoria Terrace in the end of the village, from where the Llanberies trail up to Snowdon begins. A return ticket was £3.20 (February 2012) and the journey takes 20 minutes. Going back to Caernarfon I took the bus from the bus stop in the village. It is bus number 88/89 that runs between Caernarfon and Llanberis.
If you want fantastic view of Snowdonia, but can't be bothered to walk to the top like the ambitious hikers you'll no doubt pass on the High Street, then there is a much more sedate way of doing it.
At the entrance to the village you'll find the Snowdon Mountain Railway. This takes you close to the summit of Mount Snowdon, the highest mountain in England and Wales.
The journey is a bit of a trek and a round trip takes two hours, although you can get a singles ticket and walk back down if you so wish. Once at the top there really isn't a whole lot to occupy you, apart from a cup of tea and some photos.
Down in the village you also have the obligatory gift shop and a 12 minute video on the history of the railway. This whole area of Wales seems to have more old steam railways than you could shake a stick at and I'd say this is one of the more offbeat things to do.
Be careful to pick a clear day when you'll actually be able to see out of the train and not freeze your rear off. You can get tickets in advance by telephone and this is recommended especially during school holidays. A single adult ticket is 11.00 GBP, return 15.00 GBP.