Thank you, LindaD, for the great topic. I'm learning all kinds of new, useful tricks!
Sunscreen has always been my issue but, if flying to the port for a tropical type cruise, I buy in port. I have a 3.2 ounce tube for the stuff I use on my face daily, anywhere, so it goes in my 3-1-1 bag. I also have a crushable strawish type hat, it's one of those made with a high SPF material? I wear that outdoors. It's pretty handy with it's adjustable neck strap and I fold it up in my tote while on the plane/car, etc. Got it at Costco and I think I have 5 or 6 in 2 different styles now--one's in my car, one I wear gardening, etc, and the newest (and cleanest, LOL) is saved for travel.
Shoes, as others have said, are the biggest space hogs! I normally wear trainers and pack a pair of Teva's for wet situations and to swap out day to day walking/touring. I also pack a pair of dressier, but low heeled, sandals and ballerina type flats that go with everything. My feet decided they didn't want to walk in heels about 10 years ago, lol!