my friend (who does cnd pedi's, waxing & massage) and myself do mani/pedi parties, they're fab.
we tend to stick to a maximum of 4 if they're all having spa or solar treatments as it makes it more relaxed, we don't feel as if we have to rush to get through them as quick as poss, it makes it a relaxing time for the clients too
we don't (as yet) offer a free treatment to the hostess although it's definitely something we would consider doing.
Ours are normally either a morning or an afternoon depending on school runs and kids holidays etc.
we don't do the games aspect of it, not sure if you could incorporate that into the theme as the relaxation and chat is normally enough to make it an enjoyable afternoon for all concerned.
the best thing would be to not only get more ideas off the Geeks but also ask a few friends how they would like their mani/pedi party to be (if they had one)... would they prefer a few glasses of wine and fab conversation with their friends? or do they want to make it more of a 'party' atmosphere?
I'd go for the wine and convo but then i love chatting and like a glass of wine too... ok then, i lied, i love a bottle of wine and a good old natter pmsl