I smoke more alone then I do with friends, but that's mostly cause I'm usually alone and I like smoking, not because I have a particular preference for being alone when I smoke. I like smoking alone about as much as I like smoking with friends, depending on the situation really. Sometimes I'd rather smoke alone and sometimes I'd prefer to have company.
The unique social environment around weed kinda annoys me though. If I bought a gram of dope I wouldn't be expected to give some away to every distant acquaintance I see. Yet with weed people always expect you to share all the herb you've bought with them. I don't mind sharing with friends, but when every person I've met in the last few years expects me to go buy weed and roll a blunt with them then it gets annoying as hell. I'm poor, I could afford to act that way when I was buying Mexican schwag, but since I've been buying chronic it's become ridiculous to hand weed out to every mooching half-friend that comes around. If I'm at a party (rare) and I want to smoke I have to go find a secluded space to smoke with 2 or 3 friends, because if I try and smoke around other people then I'll only get to smoke two or three hits from the gram of weed I spent the last of my cash on.
Recently I bought some weed from a guy I'd never bought from before and he asked me to smoke him (and the 3 or 4 people he was with) out. I was dumbfounded, dealers aren't supposed to bum weed off of customers, especially right after I saw the half oz he had with him, that just strikes me as dumb. If anything, dealers are supposed to smoke out anyone who buys from them. Chronic dealers are pretty much always ripping you off anyway since the normal price of chronic is so high. I just shook my head and told him I didn't want to smoke right then. Then I walked 200 ft away and lit up a bowl with two friends. If someone acts as a middle man for me I'll smoke them out, other then that they've gotta be my friend for me to feel good about smoking them out. Pot seems to be the only drug for which this is a problem.