Traveling with Camera - Sling Bag or just Strap?

I’m visiting Italy in a couple weeks and want some advice. I’m looking to bring my camera but am trying to decide whether or not to get a sling bag or just hoist it around by itself with the camera strap.

Normally I’m pretty low key with my carry (phone doubles as wallet) so usually I’d just only have a camera around my shoulder and everything else in pockets.

However it’s gonna likely be 90F degrees and I’ll be walking 10,000-15,000 steps daily, so comfort is king.

Should I get a sling and keep everything in it or just get a more comfortable camera strap and keep everything in front pockets.