Helmet, jacket, pants, gloves, boots, back protector.
In the beginning I thought it was very tedious to suit up, but as the leather gear broke in and I got better at suiting up quickly it's a no-brainer. In the summer I also thought about skipping the leathers for my 30-40 mph commute but the advertised TFL Cool System really works.
Black leather has always been associated with motorcycle clothes. It has always been like that and is mostly true even today. But there is a problem with black leather – it gets very hot in sunshine. Or rather, this was how it used to be. TFL Cool System® is a revolutionary innovation and means that black leather will not absorb more heat from sunshine than white leather.
Of course it doesn't feel like it's working when I'm walking around off the bike on the hottest summer day, but when I left it in the sun along with my luggage box (also black) the difference in temp felt like 10 degrees C at least.
I also used to drop the back protector on short rides as it was uncomfortable. Now it, or my torso, has broken in and it's no problem.
I guess I would drop the leathers and boots if I was just doing a very short ride in the city, but I rarely do such rides as everything I need is in walking distance.