In quiet moments I fantasise about an ultimate week in Snowdonia, traversing the park and taking in all the highlights on the way. Example itinerary :
Day one: Train to Llanfairfechan, then walk south, the whole length of the Carneddau range. You'd take in the summits of Drum, Foel Fras & Grach, Carnedds Uchaf, Llewellyn, and Dafydd, and Pen Yr Ole Wen. Sleep at Idwal youth hostel.
Day Two: Climb Tryfan's north ridge, then Bristly Ridge. Walk from Glyder Fach, across Glyder Fawr, Y Garn, Foel Goch, Mynydd Perfedd, then down to Llanberis. Sleep at Llanberis hostel.
Day Three: Walk up Moel Eilio, across Foel Gron to join the Ranger's path, then up to the top of Snowdon. Down the south ridge, and at the end of the ridge turn west to reach Rhyd Ddu. Sleep in the Rangers hostel or bunkhouse at Llyn Cwellyn.
Day Four: Up Y Garn, take in the first few peaks on the Nantlle Ridge, then descend south before ascending Moel Lefn, Moel yr Ogof and Moel Hebog. Down to Beddgelert and sleep in a B&B.
Day Five: Rest day!
Day Six: Down the Aberglaslyn Pass and then head north east, aiming for Croesor. Then up Cnicht, and gradually descend down to Bryn Gwynant hostel.
Day Seven: Walk up to Pen y Pass, then do the Snowdon Horseshoe. Sleep at Pen y Pass.
I think that'd give you a pretty good idea of what Snowdonia's about. The first four days are pretty huge but you're not carrying camping stuff. Doesn't touch the southern half of the park but that means there's plenty left for next time!