How you do make things interesting as GM when PCs are travelling

Just make the encounters interesting or out of the norm. Instead of some random monsters attacking, make them meet a weirdo who has interesting insight on the world. Instead of having a wild animal show up, have a giant animal being chased by a gang of circus workers. Make every encounter on the road something that either builds the world a little more, or is at the very least memorable.

>>54327051
I tend to treat each session like an episode of a TV show, in the sense that at the start of every session, I introduce something for the players to focus their attention on, whether it's an NPC who is being running from a monster, a road sign talking about some sort of rest stop, a wandering monster, or even a traveling merchant hoping to get some help in exchange for some trinkets.

Then (assuming they aren't assholes who forgo the plot hooks just because) I develop the rest of the session around them interacting with that scenario and either it gets resolved within that session or it becomes a two-parter.

Then again, I run a custom system and my campaigns tend to be extremely short (2-4 hours on average) so it might not work with every system.

>>54327051
The encounter leads to a five room cave with multiple encounters and treasure. Say the rest of the trip was uneventful and they reached their destination in good health with a full purse.