In reply to Matt250:
With regard to rack - take a standard mix. Placements in the Ogwen are plentiful and generally gear shaped. Tryfan East face is probably an adventure in its own right. I would spend a day hoping up and back down again rather than linking other crags since the down climb is quite reasonable and quick so you can get lots of milage in if you are quick.
Another classic chain is Idwal Slabs (take your pick), then Lazarus (as already mentioned), onto Continuation Wall (again take your pick), lunch, then head over to Grey Slabs. The adventurous will naturally do Grey Arete but this might be a bit steep at HVS. There are however equally adventurous easuer climbs in this region but adventure is definitely the watch word so be prepared.
Have fun - a great day out to be had up there.
Some more info here:
http://www.ukclimbing.com/articles/page.php?id=435