I have published the third tutorial in my 3D Tile Engine tutorial series. This tutorials moves to using vertex and index buffers to dramatically increase performance. You can find the tutorial on the MonoGame Tutorials page of the site. You can also use this direct link to the tutorial.
I will be working on another tutorial over the next few days. It will likely be Eyes of the Dragon or Dragon’s Claw but I have a few other ideas bouncing around in my brain. Stay tuned for more tutorials!