My Dragonlance 5th Age campaign meets face-to-face on average about once every six weeks. It's my longest running group, with bona-fide school friends who I've been gaming with since the AD&D days, and is the best and only way we all keep in touch since leaving school. When we get together, much hilarity and fun ensues. And maybe even a bit of roleplaying.
But in hindsight, a long campaign arc (we're doing the huge Key of Destiny campaign) is simply not the right game to run when you're only meeting once every few weeks. Plot details are lost, character development is wasted, and roleplaying slowly transforms from a game-enriching chocolate sauce into the peas you leave because you ran out of spuds. Where 'peas' are roleplaying and 'spuds' are time. Or something.
Key of Destiny isn't a sandbox campaign by any means, in fact it's as railroady as an epic plot usually gets, but it does have its subtleties and the general plot does take some thinking about. On top of that I've layered individual plotlines for each PC, so that's some added complication. The journals are okay (when I remember to do them - bad DM!) but I can't make them encyclopedic without the players seeing hints that aren't really there, and I have to be careful about drawing attention to certain clues that I think they missed because the adventure will suffer. It's a tricky balancing act.
At the current rate of play, we will finish the third and final chapter of Key of Destiny (and therefore the campaign) sometime in 2011. That's just never going to work for me. I'll be bored of it loooong before then, and it's the reason why I've looked into and recommended Fantasy Grounds as a virtual D&D substitute, so we can rein that target in by a couple of years. The next campaign I run for them will be homebrew D&D-dialled-to-11 (thanks Monte), where there are few if any long-running metaplots and I can just pull stuff from third-parties as I see fit. If nothing else it'll give me a chance to actually use some of the books on my roleplaying shelf.