Since James and I only see other people together, we've had a fair amount of group sex. Threesomes are our favorite because you can still have a lot of intimacy but the more people you add, the less that is so. Foursomes, when they are good, are more like a party, so it depends on what you are in the mood for. We once participated in a group of 7 and it was fine, but not something I'm interested in doing again.

Group sex with people you really like and are comfortable with, as well as attracted to, can make for a really lovely human connection that transcends just the sexual aspect. Bonobos (one of our closest primate cousins along with chimps) use sex as a bonding excercise, and there is something to be said for that with humans too, under the correct circumstances.