Story driven games are better enjoyed alone, to immerse yourself into their World and what not but more casual titles are much more fun with friendly company. A good example would be Mario Party.
It really depends on the game. While I don't mind "sharing" any storyline intensive games with friends, I don't think I could play a game like Metal Gear Solid or any of the Final Fantasy games with an audience. I'd probably bore them to death. Same goes for some sports games, unless they're a fan of that particular sport.
I think Arcades and Internet Cafe are good places to play games with friends, and other gamers of different skill levels since you don't need to worry about space, cleaning your room, embarrassing roommates, weird neighbors, and angry family members, or your friends bothering your family members and room mates with their bad behavior.
There are also many games to play at Arcades, and Internet Cafe with Gaming computers with many games installed on them.
Always with friends, it's not interesting to play games alone if you can play it online or co-op. In that way you can do team-work, learn new things and much more.
To be honest I like some games with and without company. Like maybe some good racing games I would like to play with some company, but if it is something like mario party 8 or something like that I would prefer myself because it just takes way to long for others to take their turn.
If I am playing a story based game I will not appear online or join a party. I want peace to understand it myself. If I am playing a multiplayer game like COD then I will be playing with my friends or I will get bored.
If I am playing the single player side of the game I prefer for play alone so I can concentrate on what I need to do and get through the campaign but for multiplayer I much prefer to have friends gaming as well for company as it can be a lot of fun and really interesting especially if you have a group of friends who share the same interests and humour as you
I'm more of a solitary gamer nowadays. But I do enjoy playing multiplayer games with people, with more of a preference towards local multiplayer. I haven't had any good online multiplayer experiences.
Mainly solo now days. I usually play N64 multiplayer when the friend I have that knows how to use a N64 controller comes over. My Wife does too, but we're usually doing our own thing.