Still wearing cotton underwear? Don't. It gets very abrasive to your skin when wet with sweat.
Hair rolls around between your clothes and your skin and the follicles get irritated. It also holds in sweat and prevents the fabric of your shorts from wicking away the moisture as they are suppose to do. Consider shaving short all the hair down there under your cycling shorts.
Wear bike shorts or bibs that fit you well. There are loose fitting shorts for mountain bikers if you can't quite embrace your MAMIL look.
I've never had to use chamois butter or anything similar. IMO, if you have to use it you aren't figuring out why you are getting the saddle sores. I don't get saddle sores.