I'd do a chilled out space, lush carpets and beanbags everywhere. you are encouraged to wear costumes. It's totally an underwater theme.
There always has to be a thumping base that you can hear for miles... its a key ingredient. it leads you to the low tent (you have to duck it get in) well, if you can get it. It has a distinct vibe, 'underwater jellyfish translucent real' which happens to feel exactly as it sounds. The bar tender, mixing unheard of concoctions, mingles with the barely dressed patrons. Floating lights and evaporated cocktails spill over the air. The light purple, flashing ues melt with the seaweed smell - and with each mermaid that enters, a new drink adds the the menu.
I would have an endless menu, but would dose people via their drinks and water it down a lot. You need to drink 5 or so to get properly stoned. That way people can exit the experience a bit earlier if they are feeling uncomfortable. I'd have a team of trip sitters on hand to look after anyone too scattered. But just provide a really chill stuff with lots of nooks to hide away in if one needed it. One of my first menu items would be 4-ho-met, because I think it is a more social version of mushrooms. So it might get people together, laughing and socialising. You want a safe but a space that encourages people to talk to each other also. I think it important to have a space to share ideas. All the shorter drugs are preferable, but there are trip sitters rotating 24/7 so nobody is left behind,