I've mixed just about every kava I've had my hands on, which is a lot of kava, usually with good results. Only a few mixtures have stood out to me though.
Fiji waka + isa/tudei from KBR is still my favorite mix. By far the most sedated I have ever been from a kava session, but the euphoria coming from the fiji waka allowed me to star alert and fully enjoy the state. It's a ride.
n@h's wow + HKC's Hiwa is my second favorite. It's a surprisingly mellow mix, great for my anxiety and muscles but there's this unique opiate-like 'heady' sensation that just made me want to sit back and slip into sleep. This is what I look for when mixing kavas, effects that become pronounced via the mixture but are not experienced with the individual kava.
My third and last favorite is Paradise kava's Hawaiian awa + BKH borogu. To be honest, a set back I had with the hawaiian awa was the lethargic, tired sluggish effect I rarely get from kava, but definitely got with this one. Mixing the borogu eplaced that with a blissful, anti-gravity euphoria that I enjoyed with all my heart. I do miss that mix but it's one of those situations where I wouldn't buy the hawaiian awa unless I had the borogu to mix it with, and I just ran out of borogu.
I'm really excited to get some Fu'u and expirament. Me and my girlfriend bought a few different varieties of kava that I've never tried so I'll get back to ya after some more experimentation (smiley: smokin)