I'm sitting here in the Poconos, looking out the window at the woods across the street from me, and it occurred to me that much adventure could be had within (and there certainly was much adventure had within when I was 30+ years younger).
How much of your campaign takes place in the places in between? Done properly, the travel to one adventure from another can in and of itself be an adventure. To a large extent, this is what sandboxes are about, but even without running your campaign in a sandbox, the places in between have the potential to challenge the players. I'm not talking random encounters but more like "random localized locations" that you can drop in between to change the pacing.
Hmm, in many ways this is what +Daniel Bishop 's series of Campaign Elements for the DCC RPG seeks to do, but it could be done on even a smaller scale of simple fleshed out encounters that include localized setting elements.
In any case, do you explore the places in between when you run a campaign, or do you players more from location to location fairly uneventfully?