The hardest pack for me was a 2 week Baltic cruise. I needed everything from workout clothes to dressy outfits. We also only travel with carryons after too many lost bag stories. I ended up doing a very tight color palette - black, white, and blue and everything could be mixed and matched. Shoes and toiletry were in my backpack, everything else rolled in the suitcase. It worked!
We have a three week trip planned for next year and I will do the same. The key for me is wearing the hiking boots on the plane. Not the most comfortable but they take up the most room. I plan on also bringing a pair of sneakers, one pair of dress shoes, and one pair of sandals. The hardest part for me is always the shoes ; )