I wear dockers and a polo everyday to work (keep a coat and tie at work just in case). Looking for the same thing, I ended up getting a pair of
Arlen Ness pants from Competition Accessories. I wanted something that would keep my pants clean. They work, but I'd recommend something similar, not these. They have full length leg zippers that make getting in and out easy. The thigh and knee pads are removeable (but are not CE). Are waterproof in a 30 minute downpour, but not a 2 hour driving storm. They sound good, and they're marked down to 99.99 from 139, but I've had to replace every zipper which just about doubled the cost. You get what you pay for.
Aerostich
Dariens are suppose to be the absolute best riding clothes you can buy, and you'll rarely see a beemer GS driver in anything other than Aerostich, but for the price, I'll buy a nice pair of riding pants and a set of tires!