Pontius Navigator, an "outdoor sports" shop has a wide assortment of trousers with extra pockets; but the problem with those is that you'll have to remove all metal items in the security check, where you can just take off a gilet for the event.
I recommend a small backpack as carry on: keeps both your hands free and you can manoeuvre far easier than with a rollerbag. Good thing is that many backpacks come with a lot of side pockets. I like to have pockets in my (button-down) shirt for passport and boarding pass.