Other than our infamous 5th seat which we just cannot, for some reason, fill for any length of time.
We actually had some really nice folks sit in that fifth seat for a few sessions but then they had to bow out due to scheduling conflicts, and were actually really nice about it (as opposed to most people who just disappear with no explanation). That was a nice change.
I've been gaming online (mostly in Hussar's group) for about 6-7 years now. Aside from a small handful of one-off games I played for a few months in high school it was the only way I experienced gaming.
My husband and I recently found a live group to play with, but we have not stopped going to the online game. I don't think the thought even crossed either of our minds until I came across this thread and started thinking about live versus online gaming. If somebody put a gun to my head and told me I had to limit myself to one gaming group I'd drop the live session and go back to playing solely online.
As someone who plays both an online game and a live game every week (or just about), here's how I'd compare them:
Online game gets a big plus for lack of a commute. I get home from work on Monday, eat dinner, take a shower, and sit down to game in my PJs. On the other side, we need to set aside half an hour to get to the live game, drive there and back in the dark, have to worry about snow some nights (last game we couldn't make it up the host's driveway because of the ice). And as someone with allergies I'm damn lucky that their dog doesn't give me many problems. We just as easily could have found out that they had cats and that I couldn't stay there for more than an hour before I become a sneezy, wheezy mess, unable to breathe.
Online game also gets a plus for gaming aids. My character sheet is built into the VTT we use. I click on links to automatically roll my attacks and add in all the bonuses. I don't have to remember to add my STR bonus to that special attack because the macro does it for me. I was so not used to having to work off of a paper character sheet from the live game, and having to pass around the PHB in order to look up rules seemed like such a waste of time when I was used to being able to search the Compendium or SRD in a few seconds. I have been seriously tempted to bring my laptop to the live gaming sessions for the SRD search alone - the only thing stopping me is the lack of space at the table we use.
Live game does get a plus for social interaction, but in my opinion it's not that far beyond the voice chat we do in the online game. I'm actually more comfortable socializing with the folks in the online group, but that could be because I've known them longer, though I haven't met a single member of the online group in person (well, aside from my husband, but I was the one who introduced him to the group).
Online game gets another plus for the variety of players to choose from. When your fellow gamers can be from all over the country (and even across the globe) you have a higher chance of finding a group that matches your play-style, though it may take some time. With a live group, unless you live in a massive city, you will eventually run out of people to game with if you happen to not find a group that suits your tastes. Heck, I'd go as far as to say that the high dropout rate for the fifth chair in our group has been a good thing. The incompatible players weed themselves out.
I said earlier that I'd drop the live game if I had to choose between the two of them. Luckily I don't. But having experienced both sides of this I think I can say that online play IS real D&D, and it is not second-class gaming. It's just as fun as the "real thing".