1. Jersey dress.
Because you can throw it on whenever you're unsure of the dress code—say, for a night at the theater or a dinner with your friend's friends. Opt for a synthetic blend so you can roll it up to practically nothing in your bag and pull it out with minimal creases.
2. Printed scarf.
Make sure the color palette goes with everything you pack and you'll always have a cozy, stylish accessory for museum visits and overly air-conditioned airplanes.
3. Statement earrings.
A bold pair can single-handedly transform a strolling-on-the-boardwalk sundress into a dancing-the-night-away getup.
4. Ankle-length pants.
Even with a simple top, these are sharp enough for a business meeting and Hepburn enough for a shopping trip. Look for a style in a dark shade (for optimal versatility) with stretch (to resist wrinkles).
5. Metallic shoes.
Walkable wedges, flats, or sandals in silver or gold give you the flexibility to go straight from a day of sightseeing to a swanky restaurant.