I always build starter worlds for my friends on peaceful
aka a small shelter or a cool castle.
Btw, You should use MCedit to speed things up
Yeah, I used MCEdit a bit already.
I used its chest imports. I used INVedit to give myself some more things. I am going to use it probably to fill in some caves that I found. And remove some unwanted dungeons.
The first part is underground, it uses a lot of redstone technology in it. It will have hidden staircases, most likely. Probably not lots of mob areas, though, as I have found a rather large gravel pocket which I do not want to deal with. Unless I can dig past it or get over it and dig it all out, I can't make rooms large enough for mob spawners. So, that may be a problem. Of course the first part won't be long, so that won't matter much anyhow.