In reply to highlanderwolf:
The easiest approach is supplied by the more popular routes at Tremadog and one step in the clouds and poor man's peuterey are round about severe/hard severe.There are other lower grades here too.
There are loads of good routes in the pass(Llanberris), albeit with steeper and longer approaches, and probably more intimidating exposure.Wrinkle is a good V Diff, possibly with less gear than some in that grade.Flying Buttress is an excellent V Diff.Nearby is another good V Diff with exposure,Spiral Stairs.Crackstone Rib is a really good Severe.
You probably need to get hold of either Paul Williams old guide(still published)Rock climbing in Snowdonia, or the Ground Up North Wales Rock guide.
If the weather is poor in snowdonia and possibly Tremadog, you could always try Holyhead Mountain on Anglesey.
Rob