In reply to Oujmik:
Grooved arete on Tryfan is indeed excellent, as are most of the other routes on the East face.
For a good long day out try starting with a route on Idwal slabs, then the continuation walls above, once at the top, traverse right and climb Central arete on Glyder.
Another good link up is Sub Cneifon rib & Cneifon arete, or substitute Sub Cneifon rib for a route on Idwal Slabs.
Carnedd y Filiast is well worth a visit, but there is a general lack of gear so go prepared for long run-out sections.
Clowyn y person arete is pretty special too.