@bmom,
Oh yeah, I'm not advocating spanking at all.
Sounds like the time-out consequence usually works -- I think it does point to consequences being a way to deal with it. Punishments can include taking away TV time and computer time as well.
Maybe try some proactive stuff... it sounds like she's spending a lot of time on her own (TV, videogames, bikes outside), maybe she needs to have more social time? Either with you (which could be part of the sassing -- it gets attention from you even if it's not positive attention) or with other kids (it sounds like most of that is solo but I can't tell).
So maybe set up some sort of activity for her, either with other kids if that's not what she's been doing, or with you if she has been spending time with kids.
My quick read is that she's bored and undersocialized right now (summer) and the sass is coming from that. Is she an only child?
(Good stuff from Punkey btw, welcome to A2K if I haven't welcomed you already.)