D&D's Terrible CR vs Overly Balanced Encounters
If D&D's CR is notorious for being bad and having nothing but perfectly balanced encounters is long term boring, why not just stick to CR religiously and let the two problems cancel each other out?
Finally, if the characters are traveling anywhere with risk you can define some traveling roles like who is scouting, who is trailblazing, and who is provisioning. Have them roll checks on these jobs to give you some interesting ideas about what might happen along the journey.
I do this. I learnt it from a game called Torchbearer which features a travel subsystem. The journey gives you a toll based on how far it is, what sort of terrain etc. To pay a point of toll you need to expend a ration of food and one of water, else you can pay it by having equipment break such as shoes and armour or you take horrible conditions.
You can take a role on the journey which increases your individual toll but allows you to do something that will benefit the whole team. A scout gets a chance to save against encounters. A hunter or forager will test to find food. A cartographer will map progress. A cook tests to stretch those rations. A guide is essential to get to the destination.
A difficult journey has resulted in the party sacrificing their animals which is something I'd never seen happen in any other system!
I'm working on a spherical dungeon. It contains many monster factions that are bound to anchors so they cannot leave their areas. As the players destroy the anchors and beat the factions the strength of the other anchors all increase leading to the factions having access to each other's spaces. The deeper the faction's anchor is beneath the surface the more they benefit from the expansion of their range.
I'm running Burning Wheel. The group are wizards on the cusp of the fabled third age of magic. I'm using the Trilemma Adventures as well as the setting from the book. I've got seven players so I'm just over the stressful threshold.
It's absolutely awesome.