I'd vote for a rogue/bard build. Probably using one of these:
Rogue 1/Bard 19 - Simplest model.
Rogue 1/Bard 17/Chameleon 2 - This one gets a reselectable feat (great for making magical items)
Rogue 1/Bard 6/Chameleon 2/Unseen Seer 1/Sublime Chord 2/Unseen Seer +8 - 9th level sor/wiz casting, the floating feat and near epic ready
Stats aren't much of an issue, with the first build getting by with being Human with 10 int and 12 cha. There are skill points aplenty. Probably focus on Disable Device, Search, Spot, Listen, Use Magic Device, Perform, Diplomacy. 7 usually essential skills for the bardic skill monkey, and all are able to be maxed on a Human with Able Learner and 10 int. As the builds get more complex, you will need more int to provide skill points for prerequisites, and more charisma for higher level casting.
Alternate Class Features to look into:
Bardic Knack - use half your bard level rounded up as your effective ranks for all skills you can use (if they don't have higher ranks). All your secondary skills now have a level scaling bonus.
Healing Hymn - Have the healer use less resources healing. Most useful when you don't have top up items (e.g. wands of cure light wounds/lesser restoration)
Feats to look into:
Able Learner - Pre-req for chameleon, plus you can max all the rogue skills your bard side doesn't have, without paying twice the skill points. Human only.
Song of the Heart - Boost your inspire courage bonuses. Everyone loves you.
Craven - Your level in extra damage on sneak attacks. Which is easy with Glitterdust, Grease, (Improved) Invisibility, or Blink.
Knowledge Devotion - like weapon focus and specialisation, only as one feat. And better. And fed by bardic knack.
Melodic Casting - Replace concentration with perform for casting spells. And cast spells whilst using bardic music.
Precise Shot - Avoid shooting your allies. Is also needed for a splitting bow, which is probably a good item for you.
1st to 3rd Level Spells to look into:
Improvisation - A floating pool of bonuses to rolls, useful for when you know your going to need to be rolling above average.
Inspirational Boost - More inspire courage boosting. More people loving you.
Grease - Disarm, Un-grapple, or best yet, make targets prone or make them lose their dex bonus. Yay sneak attack.
Glitterdust - Blind people. The party takes half the hits from martial enemies. And they lose their dex bonus. Yay sneak attack.
Invisibility - Good for sneaking. Also, yay sneak attack.
Alter Self - Added mobility or defence.
Haste - Extra attacks, mobility and minor number boosts. Fantastic.
Blink - Get missed by attacks and targeted spells half the time. Take half damage from area damage. Strike as an invisible, ethereal creature. Yay sneak attack.