Other than the things previously mentioned about quality of construction. to me, layout is very important. Depending on the size of the humidor, having a good balance of shelves that come with it for singles is nice to have. I am also a big fan of having glass for display. I love the wood boxes you have made, they look amazing, but if I have some cigars I like to be able to see them to enjoy myself or if I am going to share with someone I like to be able to have them visible with at least one row for viewing, makes it easy to pick and shows off the sticks that you want to show off.
Having a little slot made specifically for a cutter and lighter would be handy to have as well. I always end up tossing mine onto a shelf, but would be nice to have a custom grooved slot for them to go.