I travelled with cheapo Ryanair to and from a business meeting in Scotland (meeting 2 miles from Ryanair's airport), in my suit of course, a rare commodity on many Ryanair flights. And nosing around the airport at Prestwick on my way home got me into the otherwise closed and locked Business lounge right next to the gate, on my own.
I could hear the crowd baying at the gate outside and was getting ready to join them when to my surprise the gate agent opened the door, said "um ... we're ready for you now sir", and let me out ahead of the other 100 or so jeans and shell-suited travellers, who all instantly fell quiet and gaped. It must have been quite a scene. So you see, a suit can get you priority boarding on Ryanair, which many would say doesn't exist.
Quite separately, I notice that suits seem to have disappeared almost entirely from C class intercontinental flights. Even those who come straight from the office to evening flights seem to get changed first nowadays.