I know there's ways to force Sublime Chord to fit, but it isn't elegant, and I won't do it. Also, I want at least 9 levels of Spellthief so that I can actually store 9th level stolen spells. And I doubt the game will last beyond 10 levels anyways; seems to be about the lifetime of most games I've played in. shrug
If I find myself around L6 likely to last until the mid-teens, I'll beg to reformat my skills in some manner so that I can get into Virtuoso and do just that. Something like:
Whispergnome Spellthief 9 / Divine Bard 1 / Sublime Chord 2 / Mystic Theurge 8. Its very, very clunky, though.
So, let me clarify: I'm looking for advice on these first 6-9 levels. I know its all about spellcasting after that, and its easy to make it happen. There's virtually no really good advice for Spellthieves at the low-end on the boards; just some random threads here and there.
You won't be able to steal 9th lvl spells. You'd be able to steal up to 9 spell levels, but a max of 4th lvl spells.
As Complete Adventurer (pg 16) says:
As a spellthief gains levels, he can choose to steal
higher-level spells. At 4th level, he can steal spells of up
to 2nd level, and for every two levels gained after 4th,
the maximum spell level stolen increases by one (up to
a maximum of 9th-level spells at 18th level).
So stop at an even Spellthief level?
Good skills for what you want could be Use Magic Device, Diplomacy, Bluff, and Know (local)
Good spells?
Light, Ghost Sound, Prestidigitation, Mage Hand, Dancing Lights, Message, Detect Magic, Read Magic, etc.
I don't know if you can get Nerveskitter (lvl 1 SC). Initiative is good. Maybe?
Shield (lvl 1 PH): Only if you need it.
Grease (lvl 1 PH): Because it's annoying in battle
Improvisation (lvl 1 SC): Bonuses to skills, and probably nice for RP too.
Alter Self (lvl 2 PH): Good for RP and actually can get you some nice movement modes or Nat Armor.
Glitterdust (lvl 2 PH): Reveal those invisible foes!
Pick the best for your free Spell-like Abilities, of course.
I dunno about feats though. None of them really seem to stand out since you won't get Bardic Music, Bardic Knowledge, or real Sneak Attack.
Master Spellthief the feat would work if you somehow get another arcane casting class. It'd make the base lvl classes stack their caster levels and also increase the max spell lvl you can steal. It also gives you no arcane spell failure for light armor (for the other casting class)