Responsible is a word I love to hear. I am so glad you are responsible. To help you in your project I would recommend:
1) Centralized communal area, someplace people can get together. So a small family will have one and as the groups get larger they too will have larger ones. They can be dedicated to exercise, games, children, or sex, anything really.
2) Personal space. Not just a good idea, but a really good idea. I certainly would like to sleep in a pile when I can, but hey, maybe my lover ate the bean burrito? Time to find my own room.
3) Community. I can't handle twenty lovers. I can't tell them all how much I appreciate them so you will need ways to interconnect everyone. Local servers for the computer, some places that people have to pass though in a day as they go to work or stay home. so people can post notes to eachother and sideswipe for a kiss.
Well that is all that hit my noodle. If you like the suggestions chat with me and we can see what more can come of it.