I've been playing Sona in both Classic and Domination (I'm level 14), and am queueing for Draft for Classic and Blind for Domination.
For Classic, I seem to get shouted at for not warding (because I spend all my starting gold on the Meki Pendant as suggested by the item list, and all following gold on mana regeneration items), shouted at for attacking minions in my lane (because apparently I don't need gold and only a portion of XP). I've had people intentionally feed because I was attacking minions, and told me to go AD Carry, boots and all. >_>
So clearly the Riot recommended starting item set for Classic for Sona is completely wrong according to the people I've been playing with. I've been on a League of Legends build calculator to try and work out a better strategy that includes more mana regeneration AND sight wards but nothing seems to work short of taking Clarity (which robs me of a Summoner Spell later in the game when Mana stops being an issue).
My Mastery build for Classic so far:
4AP and 4% Cooldown Reduction in Offense, Summoner's Insight, Expanded Mind and 2/3 Meditation (going for the extra CD reduction in Utility). Ususally take Teleport and Flash as I sometimes have to port back for mana.
I'm doing far better in Domination, except that I don't like the on-use item (Odin's Veil) because they have very small icons that I have to click (unless someone can tell me if there's a keybind for it). I drop an AP in the Offensive tree for Summoner's Wrath, drop one out of Meditation for Archaic Knowledge and swap the point in Summoner's Insight for Improved Recall or one in Good Hands (depending on how other games have gone). I occasionally get namecalled for capping the first tower out of the upper walkway, but apart from that I've had up to almost 30 assists just by latching onto anyone I could keep up with and wanted me. :3
I use Exhaust and Ghost in Domination.
The other problem I've had with my Domination build is either the team don't do so well and I'm no-where near finishing my item list, or we do so well and I have an extra slot (as the blue mana gem in the first slot is used for the Archangel's Staff later on).
My runes are a mess (as I've just got back to playing and found out I can't Sivir all that well any more):
3x 4.59 mana red
1x 0.42HP/level red
3x 0.05mp5/level yellow
1x 0.74 magic resist yellow
4x 0.24mp5 blues
1x 3.24 mana/level quintessence
That's about it.
So yeah. Halp?