Sneak Attack is great even with a dip if you've got extra attacks - it's kind of meh otherwise.
In general, though, Dragonfire Strike + Bracers of Murder is pretty solid, even with a dip. Dragonfire Strike increases damage by 1d6 and turns it into energy damage, while Bracers of Murder give you some nice attack bonuses (rerolling 1s isn't worth a feat, but it's nice to have anyway).
It costs you two feats (or you need to play a Dragonblooded race), but getting +2d6 Fire damage on any attack you make vs. flat-footed people is pretty decent.
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Basically, if you're not working to pump up your sneak attack damage, you need to look at it less as "my main combat tactic" and more "some nice bonus damage I get sometimes".