You can make simple games and your friends can play them like some of Roosterteeth's Lets Plays or you can build a small/big RPG village for people to play in it, depending on how much people will/dedicate to playing it.
For survival, gets a couple of firends and just get ore, build houses and defeat the Ender Dragon if you are currently taking a break or have nothing to do.
What kind of terrain are we talking about here? I've always been a firm believer in working more or less with the terrain.
If you're in an area with long sweeping hills and flat valleys, hilltop houses with tiered gardens and overhang balconies looking out over a town (blacksmith, farm, etc) always look lovely.
If you're in a desert, you could try building a pyramid or a temple with lots of sandstone buildings around it, and make a nice desert oasis.
If you're in a mountainous area, try building pods in the mountains and sticking out of cliff faces. With bridges linking two parallel cliff faces together, and with and intricate stair/elevator system in the hills, you'll end up with a quirky and unique hobbit city of sorts.
If you're in a flat land with lots of water around, such as ocean fronts and rivers, you can build floodgates/boatlocks, a lighthouse, a big ol' port, and a coastline town.
Do your best to let the terrain inspire you.
build a single mass complex that goes from bedrock to sky limit. the center should have the end poratl in it since you can't move that. you can have hanging gardens, underground farms and a central mine cart elevator for quick movement.
I am doing this! Now I have to find a lot of lava....
go branch mining at lava level roughly below y10-y12. That is where you would find plenty of it... Although I was trying to make a tree farm underground and ran into a couple pools, which is where I got the idea for myself...lol Ironically though the lava storage ended up along side the trio of tree farms, but at least I got it somewhere safer away from the trees. ><
Glad you like the idea...
Of course I am still working on it since I had to decide carefully now where exactly to put the lava. So a tip is to put it somewhere a bit further away from any wooden constructs and tree farms you may have.:)