City-and-beach combos are the hardest trips to pack for, because you are packing for two climates and two social codes. The answer is not a bigger bag — it is a smarter set of clothes that cross over.
Build in layers, not outfits
One pair of comfortable city shoes and one pair of sandals beats three outfits. Clothes that layer — a light shirt, a breathable layer, a foldable layer for evening — cover museums, mountains and restaurants alike.
The beach stuff that does double duty
A quick-dry towel that is also a blanket, a big scarf that is also a cover-up and a sun hat that survives being packed. Beach gear that packs flat turns carry-on into a realistic option.
Wash smart, not often
Two or three outfits in rotation plus one 'nice' outfit covers a week if you rinse light things in the sink. A mid-trip wash keeps everything fresh without a second suitcase.
The rule that ends overpacking
If you would not carry it up three flights of stairs in the heat to your room, it does not come. Lay everything out, cut it in half, and keep the tissue paper out of the bag.