Husband and I just did a combined rural-urban trip:
1) Fly to Geneva. Ten days hiking across the Swiss Alps, requiring heavy boots, poles, emergency mountain climbing gear, and cold-weather layers.
2) Train to Milan. Ten days in the most famous Italian cities for sightseeing and restaurants, requiring lightweight, dressier clothing. Fly out of Rome.
After some head-scratching, we got it all into carry-ons out and back using the following system:
1) Pack for mountain trip, including one or two decent non-hiking outfits per person.
2) Cross Alps. End in Zermatt.
3) Go to the Zermatt post office. Mail home all the mountain climbing gear and clothes, which almost emptied our packs. They have excellent, sturdy boxes available at the office and had no problem with packing on the spot. Swiss Post Economy class charged us $100 to send forty pounds of stuff back to California.
4) Take a train to Milan, hit the street market, enjoy the fresh food and flowers. And by the way, they sell clothing. Pick up a few extra socks and shirts and lightweight pants by that famous Italian designer, Il Cheapo.
5) Enjoy Italy.
Benefits: Easily changed flights without concern. No lost luggage. Skipped straight through customs with our light carry-on bags, avoiding the long line for checked baggage. Did not have to carry an extra forty pounds all over Italy. Well worth $100.
I would not recommend mailing things home by Italian Post unless you never need to see them again. Use a private mailing service from Italy. However, if you have to carry a lot of gear for a specific event, this system worked great.