In my experience, the best mix for 2C's is with Mescaline. I once tried a mix of 15 mg 2C-E + 15 mg 4-Aco-DMT - plus a gram of shrooms for good measure - ;-) and sure, it was a crazy trip with wild visuals. But at the end of the day, I didn't get a whole lot out of it. It kind of felt like the phens and tryps were fighting for dominance and caused a lot of confusion and wild mood swings. I appreciate the analytical clarity of the 2C's and this combo messed it all up. Whereas mescaline (at least for me) is always a smooth, gentle ride with a far superior body buzz. So, one day I decided to do an estimated 350 mg Mescaline (San Pedro cactus extract actually) + 20 mg 2C-E simultaneously.
Yeah, I like to trip pretty hard sometimes and in retrospect, it was a bit tooo much - I would probably reduce the dosage to 200 mg and 15 mg next time. But still, this was one of my top 3 trips EVER. The mescaline completely "smoothed-out" the harsh 2C "edge" and resulted in a nearly perfect mix of positive emotion and analytical depth. I've had a few really good acid trips and if I had to compare this mix to anything, high-dose LSD is probably the closest comparison. (Of course, there was a lot more cardio stimulation than with acid). Anyway, Mescaline rocks on it's own too. If you haven't tried it you really should put it at the top of your list. When you get a good feel for it, I'm willing to bet that adding a little 2C-I or 2C-P on top will completely blow you away!
Anyway, that's my 2 cents. Happy trails...