That's what I've been doing too. After RoA, Lichbane and the Sorc Shoes I start thinking about what to do from there, usually a BV/Deathcap, but last item I can never decide between the Rylai's or WotA.
Still deciding what to do with runes, so far Move Speed Quints, Mpen Reds, AP Blues and MP/5sec Yellows.