I'm going to have to give it to The Sims 4. I never thought it would last this long, yet it's been going strong for eight years, practically a geological age in gaming terms. Typically, you won't see any Sims 4 packs go on sale unless it's a holiday or a new game pack's been released. In this case, it's the latter. But before you get your hopes up just know the new game pack -- My Wedding Stories -- isn't included in this deal. What is included are almost all of the expansions, game packs and stuff packs at Amazon for up to 52% off.
As a longtime Sims 4 fan I want to encourage you to get all of the expansions and packs, but as a thrifty person I do realize that would be a lot of money to spend at once, even with a sale. So of the items on sale, obviously start with The Sims 4 base game, because you can't play anything without it.
The rest my suggestions are based on my playing habits, but I think it's worth it. The Sims 4 Seasons is a must because without it, there's no weather. If having a career you can walk into and interact with in your world matters, Get to Work is essential. Then there's City Living for apartments and University for advanced degrees and jobs. I won't even go into the game packs and stuff packs because there's far too much to cover, but I will say that you'll have a good time grabbing a few of these too for more immersive gameplay. Expansion packs are $20, game packs are $14 and stuff packs are $7. Right now, you can beat these prices, but you only have today to do so.