Weogo and Lee,
I should have been more specific. The type of parties/settings he (my friend) is thinking about are actually small gatherings (10-20 persons)sitting on a terrace (i.e. only one room) that is about 18ft x 13ft and 10ft height, open on two sides (actually front and side). The music is mostly just over background-level, but good quality is expected. The volume is sometimes cranked up, but never at PA levels.
I have two tapped horn subs (homemade, small 60-150Hz), and I was thinking about the mains. The SH100 are a good wide-dispersion solution, but for the specific application I have the feeling they are overkill. I was rather thinking along the lines of Hi-Fi/home speakers or ceiling coaxes. Near ear-level placement is in my opinion more natural that sitting under the source, but getting uniform dispersion is the problem.