Okay, here is my adventure so far. I've only been playing for a week now, but I've been playing ALOT. This game is too much fun!
I started here:
I spawned in a sand crater at the base of a mountain. The ocean and beach is just outside the crater. Lots of sand. So I dig out the entire crater and get something like 30 stacks of sand, not to mention lots of dirt and stone.
So I recreate the crater floor in dirt and bury myself underground to keep myself safe from the baddies at night, and decide to build my stronghold here, nestled against the mountain and inside the crater. And I dig out a whole crapton of stone to build my fortress out of.
And here is the result:
I started by walling the mountain off in stone and torching it up to keep me safe. This didn't go as planned at first, as I had many breaches over the nights. Slowly I learned where my walls weak spots were and fixed them. I had more than one surprise creeper blow a hole in my keep as I built it!
Once I had a safe perimeter, I could build by both day and night. The keep goes part way into the mountain itself, and then the spire goes upward, using the mountain itself as support. I made sure to place many balconies and overlooks. I also used alot of glass, as I had plenty of sand to cook up.
The courtyard has a waterfall that I tunneled out to the ocean, I can plop my boat right outside the keep and sail out to sea, day or night. I also have a small garden. I'm going to redo the garden tho, it's layout could use improving.
After a bit I got tired of waiting for daylight to cut trees down, so I walled in an area to grow a tree farm so that I could safely cut wood at night too.
The glass area in the courtyard is a skylight for my mineshaft. The shaft goes straight down, and is very well lit by day because of this. Also it's cool just to be able to look down my mine from the courtyard!
Still lots to build, it's far from done yet. And I've mined into a HUGE network of caverns underneath the keep. I still haven't fully explored it all. I did mine into the ocean floor by accident once, that was fun! This game is damn fun.