What zones to skip/do on a somewhat "boss rush" run?

So, I won't drag out the intro since I've posted it once or twice already, but I lost my lv 220 "completionist" main save with 400+ hours a year ago, and finally started a new character recently to eventually do the DLC content.

I asked for suggestions last time on how to keep things entertaining, and someone suggested looking up "boss rush", and to that I was pretty shocked at how much content in Elden Ring is optional.

That being said, I'd be pretty underleveled if I "just" did the boss-rush for the DLC, and lacking a lot of options/talismans/tools/whetstones/weapons/stones/great runes, etc that I'd wish I had.

So I'm wondering, what are some zones or quest lines I "definitely" should do in your opinion?