I think you can look at more than just herodotus and pausanius for spartan religion and festivals. These are some that I can recall offhand:
Hyakinthia - Athenaeus (Ancient) says it is both a mourning for Hyakinthos and praise to Apollo - Hooker (Modern) says something similar, although I can't remember it
Gymnopaedia - Plato (Ancient) praises it, "by dancing strenously in the summer heat, Spartan warrior trained in both musical grace and warrior grit" (I think that's it word for word actually!)
Apollo Karneia - keywords is the main deal - straphylodromoi, agetes, heracles, agoge division, divination - if you've studied up, you'll know what they mean.
THere's alot more, but that's somewhere with my notes - I'd probably have to dig it up for you! Anywhos, this website has a fair bit of information on Sparta, seeing as its so popular - so check the notes online as well!
Hope that helped?
Good luck 08'ers! =)