Lifthrasil: Ultima 7
While you can't switch off the monsters, nothing forces you to follow the plot. You can just wander the world, seeing all the sights. Especially after you stumble across the magic carpet you can go on a vacation anywhere, without understanding what the different plot elements mean that are standing around.
dick1982: or you can just cast the Armageddon spell. heh.
likewise, you can cast that spell in most Ultima games, which pretty much "empties out" the whole game world.
There's only 2 Ultima games that have that spell.
(Also, if you are going to cast this spell, make sure to save before you cast it, and *not* to save after.)
MasterW: I remember reading a series which was called something like "Life as an NPC". This was about someone who tried to live in TES4 Oblivion as an NPC. So he slept in a bed at night, ate a few meals a day and had to brush off everyone who would offer him quests or anything related to combat.
Sounds pretty boring but the whole journey was actually very fun and interesting to read.
There's the occasional JRPG that has a section like that.
Perhaps the most famous example (or at least the one that I'm familiar with) is in Dragon Quest 4, specifically Chapter 3. At the start of that chapter, you can literally just wake up, go to work at the shop, work until night fall, get paid, go back to sleep, and repeat until you have as much money as you want, no combat involved.