Monkey butt (by my definition, anyway) is specifically related to a lack of ventilation, which leads to a buildup of heat and irritation. A sheepskin helped a bit, but a beaded seat cover was a lot better for me. Either will work much better when combined with overpants that have mesh in the butt, rather than solid textile or leather which totally block airflow. For the same reason, I didn't find much improvement with bicycle shorts - the foam pad blocked any airflow and tended to hold the heat in.
If your main complaint is pain and soreness on your sit bones, distributing your weight onto a larger area of the seat will help. In other words, make the seat more butt-shaped, so that more of your butt's surface area is in contact with the seat and your weight is divided more evenly over a larger area.
You can do this to some extent with inflatable pads like the Airhawk, which will conform to the shape of your butt. They do directly increase your seat height, and the wobbly sensation of sitting on a balloon takes some getting used to.
If you are willing to pull the cover off your seat, you can reshape the foam for free. Your results will depend on how drastically you want to reshape the seat. Shave down some foam under your sit bones to reduce the pressure on those points, or add foam to build up the areas away from the sit bones, or both. In either case, try to make the seat more butt-shaped, so that no one area of the seat compresses more than another when you sit on it.
I built up a spare stock seat using spray adhesive and layers of carpet underlayment pad ($30 for a huge roll at Home Depot). I went a bit overboard, but it is super comfortable now after maybe $100 in foam, adhesive and vinyl. I used to get sore after about 45 min on the stock seat and I've done multiple 8 hour days on the built up seat without pain. I'm very happy with that.
Do a google image search on "Russell Day-Long" to get ideas on the shape. The wings along the sides can easily double the surface area that is supporting your weight, which halves the weight that each square inch of your rear end is subjected to.