All Hobbit Holes have to have an entrance. You can go as lavish or as simple as you want. With the updates in 1.8, Prismarine Blocks would be being used a lot. Some have already started decorating the entrances to their base in the Nether Hubs on servers. Many creative ideas come out of the entrances.
If there is one thing that we can learn from the Dwarves of any fiction series, is that they build underground. Often times, this is within the depths of a Mountain. Dwarves also build lavishly with fancy structure supports, homes, work places, and decorative writing on the walls.