My fun comes out of the spiritual part, I have an absolute blast getting in touch with my thoughts and running around in my head looking at strange things, watching reality warp into something unable to be witnessed by a sober person. If im really far gone and I see or hear someone(not real) talking to me and we have a chat through mindwaves, I find that immensely spiritual, this is either something that is real or something that my mind has made up purely without me being conscious of it, either way this makes me smile and its actually quite fun on the side.
Sometimes tripping can become serious though and that why I prefer to trip alone or with few people because sometimes I just need time to think and it goes from fun, happy and laughing to a deep trance of thought, not a bad thing by any means but just not what you would usually say is fun.