For protection, I'm gonna repeat Ice Shield (Frostburn), since DR 15 / - is great, and it lasts 10 min/level if you know how. And no, Heart of Earth doesn't cut it.
Also, I prefer Energy Absorption over Energy Immunity. Energy Resistance 10 to everything, and immunity to 1 attack which you absorb to heal is great (I've had my blaster nearly die, only to get a spell Spell Turned to me, which was scary, since it was a 20d6+100 damage spell, but then I recalled I had EA and I ate it to heal to full hp).
Glitterdust remains useful at all levels to find and mark Invisible foes.
Shroud of Undeath is perfect vs. Negative Energy, and is only a 2nd level spell.
Ray of the Python is pure awesome for defanging any brute.
Spellcaster's Bane is great for knowing what's happening spell-wise anywhere near.
Dragonskin is great for AC and Energy Resistance.
Assay Spell Resistance to ignore SR.
Dimension Door (Greater) for unmatched mobility.
Ruby Ray of Reversal removes any Polymorph/Wildshape/Trap/Magic Jar and many other stuff, with no fail.
Invisibility (Superior) is actually good, since coupled with Nondetection, you're untraceable.
Replicate Casting is a great spell for many things, and I'm quite sure you can use it to counter any 8th level or lower spell.