When I use Team builder, it's normally to get better at certain champions in certain lanes before using them in ranked, or other times I want to try a new champion in a specific lane with no hassle of blind pick.
So I have two suggestions.
1) When you select a champion, then a skin, offer a couple presets for default lane positions and lane rolls based on that champions history in overall matches. This will help new players learn new champions in lanes that the champions do better in. you already do recommend item sets, why not lane positions?
2) Allow users to set up their own Team Builder presets much like item presets. So I can quickly select:
- Team Builder preset 1: "Veigar Mid Lane Nuker"
- Veigar with Final Boss Skin
- "AP Mana" Rune Page
- "AP Damage" Mastery
- Middle Lane/Mage
- Teleport & Flash