Which cheats and why?

The main cheat I use is freerealestate to move in Sims who I'm not going to actively play but to give my Sims neighbors to visit, especially if I find a good family on the Gallery or a particular game-generated Sim catches my attention after a makeover. I also use mods that might be considered a bit "cheaty" like UI Cheats Extension to help create my own townies -- I'll create them in CAS, place them in the game then give them a few skill points and some of the reward traits and the Character Traits from Parenthood to givn e them a bit more flavor, like an Argumentative Sim with Uncontrolled Emotions, or an Irresponsible Sim with Good Manners. Then I set them loose in the world for my Sims to encounter.

For my own Sims, I mostly just use the Make All Happy cheat on the mailbox (testingcheats true) when I first return to a household after rotating away to take care of all the bad moodlets that seem to occur while I'm busy with another family in my rotation, especially if it's a work/school day and everyone is hungry and needs to pee but only have an hour before leaving for their daily tasks. :o