I find myself in different weather situations on a daily basis as I might be flying from Green Bay to Santa Barbara as I did a couple of weeks ago. I also find myself working in the rain fairly regularly as we fly in just about all weather conditions rain or shine and the plane still needs a pre and post flight.
The jacket I carry is mid length waxed cotton with a removable hood. It has a removable liner I could buy for it, but instead I use a cardigan sweater which I pack. The jacket I wear or carry into the terminal, the sweater is packed. This covers me for just about any weather situation I might find myself in. The sweater works when it's just cool outside. The jacket for when it's a bit colder or rainy, and both together when it's really cold along with a wool watch cap and gloves. Because it's made of waxed cotton, the jacket is breathable so it insulates well when it's dry or wet and the hood covers me when I'm working in the rain. Waxed cotton comes with a few compromises. I have to re-wax it every couple of years to maintain the water resistance. For me it's worth it because of the versatility.
I'm always flying with black pants so I have a single pair of black dress boots I bring. They are water proof enough that I don't get my socks wet walking through puddles on the ramp. I buy more expensive boots that don't wear out in short order from wearing them daily. I do pack a pair of flip flops I wear inside the hotel room and casually outside when it's warm.