I have a long list:)
We do not own an umbrella here at home so would not bring one or buy one on a trip.
I don't bring my laptop or iPad, just my phone.
I hate earbuds and actually gave mine to my husband as they just annoyed me.
I don't take noise cancellation headphones, but my husband can't live without his.
I rarely bring a second pair of shoes.
I only bring the jewelry I wear daily, with is my wedding ring, another ring and a necklace. I do bring my Apple Watch since I can use it to pay for things.
I don't bring my water bottle unless it is a hiking trip.
I don't bring snacks. Yes, I prefer to spend an insane amount for them at the airport if I decide I want them;)
I don't bring any books to read or guidebooks.
I do bring a compact travel pillow as that is what I use in hotels, but it compacts down to a very small size.
I do bring extra batteries for my headlamp as well as my old SLR camera. Nothing like trying to find a camera battery when you are in a remote area. Granted, these don't go on every trip, but when they come along the extra batteries do as well.
I too leave my husband behind on occasion;)
I don't bring the ATM card for our main checking account. We have separate accounts for travel so that if a card is compromised then it won't affect our banking.
I don't bring heavy coats as layers work best for me, and of course are easier to pack.