Beyond the Bestiary books, I've been using Mimic Fight Club to build encounters: https://mimic-fight-club.github.io/ It's really great for scaling encounters to the party size and level, and it's useful even if you are just searching and filtering.

I have noticed a lack of normal humanoid enemies though. There have been a lot of battles against Kobold Scouts reskinned as "bandits".

For treasure, I refer to the Treasure By Level chart (11-1) on page 536 and the Party Treasure By Level chart (10-9) on 509. I try to find something appropriate for the area the treasure would be in, failing that, I start looking at spells to use for scrolls or wands. I tend to use the 10-9 chart as a minimum baseline and add more on top of that, but my group tends to forget the items they have, so your mileage may vary.