Seeking Recommendations for European Vacation Attire

My wife and I are taking a long trip in October to Iceland, Italy, Greece, Turkey, and the UK, including a 7 night cruise. I’m from the Midwestern United States and understand European cruises (and destinations in general) are markedly dressier than those to the Caribbean, or the continental United States, for that matter.

Essentially, I have full suits for formal wear and a plethora of casual wear, but would like recommendations for smart casual wear (the in-between) for the trip, as to not look like a complete tourist.

Thus far, I’ve seen recommendations for chinos, short-sleeve button downs, and loafers vs. trousers and long sleeve-button downs, and never shorts. I have button-downs, both long and short-sleeve, and polos, but would like specific recommendations for loafers/trousers/chinos and what to pair them with. I’m thinking a slim fit is best in both shirt and pants.

I’m 31 y/o, 5’8”, 143 lbs, with ~33 inch waist currently, though am attempting to gain and anticipate being closer to 150-155 lbs at that time.

Any recommendations appreciated.