Although this route is a bit of a tourist trap, it's worth doing for a number of reasons. Firstly, it's quite short, and can easily be completed in a few hours if you oversleep in the morning. Secondly, it's a really nice walk, and as you'll see form the photos, the walk up the edge of the valley can be breathtaking.
The starting point is the car park at Pen-y-Pass. You'll have to get there early if you want a space, as this route is extremely popular. If it's full, head down towards Llanberis and there are a couple of car parks with a shuttle bus service to the Pen-y-Pass.
As far as walks go, this one is pretty simple. You start from the back of the car park. You'll see two paths: one to your left and one to your right. The left-hand one is the Miner's track, down which you will come, the one on the right is the PYG track. I don't know why it's always up the PYG and down the Miner's and one day I might try it the other day. However, this is the way everyone does it, so just follow the crowd.
The first part of the walk is a well-marked track over rocky grassland. Follow this for a while, and you'll see a peak in front of you. This is not Snowdon, but Cribb Goch, probably the hardest route up and certainly the most dangerous. Best not to go this way! As you reach an arête, you'll see the Cribb Goch path going up steeply to your right, just by a style. Go straight on and round the mountain, and you'll see yourself heading up the side of the valley.
Snowdon is ahead and to your left slightly, and you'll soon see the Miner's track at the bottom of the valley. From here, it's simply a case of following the back to a ridge where it joins the Llanberis and Cribb Goch paths at a marker. Turn left and continue to the summit.
To come back, retrace your steps to the marker, and start going down the way you came up. However, after a little while, you'll see a descent on the right which heads down towards the lake. This is the Miner's track. Part way down, there's a little cave which I will one day explore if I remember to take a torch with me. I don't advise anyone to actually do this, as caves can be dangerous.
Once you reach the lake, it's a wide gravel path all the way back to the car park. You'll pass some old mine buildings and some machinery made in Erith, London, on your way down.
Interestingly, although a fairly easy walk, this is the only Snowdon track which has actually beaten me, when I attempted it in December 2008. There was 2-3"-thick ice and walking in walking boots proved impossible! I've done it in the summer, and it's good fun!