Joe, you see my stock list below in my sig. I'm looking at adding a Kole Tang. I think bangaii cardinals mix well with an assortment of blennies and gobies. My mix has been together for 2 years.
4 clowns is not recommended, but mine have been together 2 years. Tank raised don't seem as aggressive.
You need to have lots of live rock for the mandarin to make it in a 75 and definitely no other pod eaters in the tank. If you can't get a mandarin to live, a hectors or rainford goby is a good alternative to a 6 line wrasse. They can be tricky to feed but will eat algae, sift sand and snack on pods so do well in an established tank.
You should consider some shrimp, either the fire shrimp which is colorful but reclusive or the skunk cleaner which is quite active. The only problem with the skunk cleaner is they steal food from corals you are trying to hand feed. My fire shrimp is great, I've had it 2 years as well.