Just remember that, at that level, you will start encountering Spell Resistance and fairly high saves in your opponants. If you are going to be on the direct offensive with your spells, you need things that increase SRP (Spell Resistance Penetration) and the DC of your spells, OR you need to focus on spells that bypass those things (like the Orb spells from Complete Arcane, or rays, which will require some ranged feats and dex).
I contemplated briefly this build that cranks SRP and spell DCs for direct damage spells.
Human Sorcerer (Cold Evocation Specialist)
Lev 1 Sorc 1 Spell Focus feat: Evocations +1 DC, Greater Spell Focus feat: Evocations +1 DC
Lev 2 Sorc 2
Lev 3 Sorc 3 Energy Substitution feat (Complete Arcane): Cold
Lev 4 Sorc 4
Lev 5 Sorc 5
Lev 6 Elemental Savant 1, Draconic Heritage feat (Complete Arcane): Silver (Disguise Class Skill, +2 v. Sleep Paralysis Cold, requirement for Draconic Power)
Lev 7 ElmSv 2
Lev 8 ElmSv 3 Energy Penetration (SRP +2)
Lev 9 ElmSv 4 Draconic Power feat (Complete Arcane)(+1 Caster level and DC all cold spells)
Lev 10 ElmSv 5 Energy Focus +1 DC (-1 Spell Casting Level)
Lev 11 ElmSv 6
Lev 12 ElmSv 7 Cold Focus feat (Frostburn) +1 DC
Lev 13 ElmSv 8
Lev 14 ElmSv 9
Lev 15 ElmSv 10 Greater Cold Focus feat (Frostburn) +1 DC
+6 DC to cold evocations by 15th lev (spell focus, greater spell focus, energy focus, cold focus, greater cold focus, draconic power).
+3 SRP to cold spells by 9th lev (Energy Penetration, Draconic Power)
+1 Caster Lev to cold spells by 9th lev (Draconic Power)(helps make up for the lost caster level at 10th)
Obviously this guy puts the smackdown on opponants with evocations, all of which are cast automatically as cold spells. Frost Mage (from Frostburn) instead of or in addition to Elemental Savant is also an option.