This may not apply specifically to your project, but I'll add in my two cents.
Since my game works primarily with 4 "hubs" and a bunch of content that spiderwebs off of it, much of what I need to do is make traversing the same ground interesting.
Generally, there are several "phases" of player exploration of my maps. The first of which is just the general exploration every player does. Move forward, check out everything, find an obstacle, clear it, get more access to the map.
However, alongside this, I have a couple other systems on top of it.
The first of these systems is "map unlocks". As the player goes up in levels, new areas of the map unlock and shortcuts back to old maps unlock. The player is never told where these are, but upon discovery of the mechanic and the short tutorial on it, it tends to send players looking around the map for what has changed. Now, the "new areas" primarily consist of new dungeons to tackle alongside new quests. The "shortcuts" on the map are tied directly to the main character's level, while most of the dungeons and quests are tied to various party member levels (usually 1 unlock per every 3 levels, but each character rotates on different numbers. Some characters unlock at level 2, 5, 8... others unlock at level 3, 6, 9... and the last set unlock at level 4, 7, 10.). This ensures that as characters level, there is always something to go looking for. Players can effectively eliminate content from an area before moving on this way, by just looking around the map.
The second system is a series of collectibles. There are 80 Silver Keys, 80 Guild Certificates, and 430 Diamonds to be found in the entire game. They are split evenly among 4 maps. Silver Keys are used to unlock Silver Doors or Silver Chests (more doors and chests combined than there are keys in the game). Guild Certificates are used to upgrade shops. Those shops can get more stock, improve prices, change stock, or other various things. The Diamonds are turned in to a Collector for "Relics" which offer gameplay twists. Things like, "Monk Doctrine" where your Strength goes up 500%, but you can't equip any armor and weapons. Players may spend some time looking for each of the collectibles for the direct benefits provided.
The third system is a "Skill Upgrade" system. There are places the player can find which will allow direct upgrades to their existing skills. For example, "Fire", which usually has a bonus damage of +10 and a 50% chance to inflict "Level 1 Burn" on enemies can be upgraded to have either a bonus damage of +30 or to inflict Level 2 Burn at 60%. Anyway, most of these upgrades are tied to a quest to complete. But, finding the location of that quest is something the player will have to do. They'll have to talk to NPC's to track down information and explore every corner of the map to find each upgrade. These upgrades can be missed if the player isn't looking for them or is ignoring them.
The final system is a "Party Member Interaction" system. There are points where a player may stay at an Inn. In those cases, if a specific amount of story, quests, or levels have been gained, you can unlock new quests for those characters which unlock higher level areas in the maps. Likewise, some dialogue in the game changes depending on who you have in the party with you at the time. A player could save some quests to do a bit later, for when they have other characters, and then return to pick it up to view the dialogue. There is also a specific set of items each character can equip that is its own storyline and mechanic. I call it "Sins", but it is merely a deep character flaw each character can overcome. To overcome it, they need to have the item equipped (with all its drawbacks active) and defeat bosses and choose specific dialogue options that only appear while it is equipped. The player can choose to engage with this system or not, but if they do, it permanently unlocks the extra dialogue options when you finish as well as changes portions of the characters so they may offer different things to do or new solutions to quests. These interactions give the players real objectives to accomplish and good directions on where to go to accomplish them.
Anyway, much of what I'm doing is just trying to make traversing these maps interesting each time the player has to do it. It isn't so much "backtracking" as it is using the space again to get to the next location. You cross back into the forest because there are new paths that opened up there. You go back to the starting village because a new shopkeeper has appeared there with higher level loot. You head back into the mountains because you've heard rumors of a Dragon living there and your main character wants to kill a Dragon just once in his life, and you think he might get an upgrade to one of his skills if he manages it. Or, you make a final run around the entire map to see if you can't find the last Silver Key in it that you missed.
