Lately, I've been going back and forth between Borderlands and Brütal Legend. A noticeable difference between them is the effect of music in Brütal Legend to make travel between missions less mundane.
Borderlands has good music. In fact, I've been surprised how many of my friends have mentioned it. But it's environmental music, accompaniment, rather than the rock songs of Brütal Legend which invite more attention.
Plus, Brütal Legend's landscape is full of monuments and amusing objects. There are trees made of exhaust pipes, beer bottle bushes, and giant stone swords sticking out of the hills. Stuff like this gives the player something to laugh and marvel at while driving around.
A little space between events in play isn't a bad thing. But it's good to offer the player something to enjoy in that downtime, so the player's enthusiasm never wanes. This is particularly important in games that are meant to be replayed.