i dont always layer, but when i do, i have been having more successes than fails.
here are a few layerings off the top of my head that have been the best for me to date:
ER 85, TWR, dot of ahmad or kannan koh. the scent of ancient times and celebration of antique and musk.
ambergris macerated and heated in sandal, then any walla oil or salty oceanic green/blue PNG oil
papuamantan with a dot or OR5 to accentuate the maroke aspect or papuamantan with dot of kinamantan if i want a brighter, more vaprous lighter green feel.