Do a "soft pack" - that's what we do before a big trip ie kids' sleepover 2-3 wk camps or 2 wk travels to Europe.
Put in what you want and then take out what you can't fit in - hahaha! Seriously. Only by putting it in and visually seeing what you have is it easier to forgo what really you can't fit. It's prioritizing and making peace with that choice - you gotta see it to realize you don't actually need it
Typically - I find bringing enough PJ/comfy evening sleeping/chill clothes is good because you just want to relax in a new room/house you've never been, away from home, after a day of long sightseeing you may be tired. I also find bringing my own pillow or travel pillow is nice because I hate the huge big pillows offered in many places. I also try to bring my own throw blanket. Believe it or not I can pack all this and not check luggage. I use the 22in Briggs and Riley that is so cool when you hit it everything it compresses - you can fit a ton of stuff and it's crazy $$ but I can pack everything and I mean everything in this bag! We just did 2 weeks in Europe and I managed to fit my blanket and 10 outfits in - dresses, skorts, shorts, tops, undergarments, etc.