How about a pair of Colorado Chaps?
http://www.coloradochaps.com/miva/me...tegory_Code=MC

 

I've commuted on motorcycles for many years.

I either wear my jeans in and change at work, or I have a pair of Tourmaster synthetic over pants. They have removable panels, mesh lining, a rain barrier and a thernal liner. I pretty much can wear them year round in the Washington DC area.

 

 

You want gaiters, I wore them all the time, keeps lower legs warm and prevents your pants from blowing and flapping.. It also prevents looking like a dork with your socks and calves showing.
Google quarter chaps and half chaps.

 

 

Motorcycle overalls would work - easy on/off over your work clothes.

 

I have a one-piece Aerostich Roadcrafter, that is the best there is to wear over your nice office clothes when riding. EZ on and off. Only problem is they are very warm. And very pricy but the quality is outstanding!
http://www.aerostich.com/suits/one-piece-suits

 

 

Let's see...
Prevent ruination via road grime and rain to your dress slacks? Check.
Non hassle to install/remove quickly? Check.
Protection? Check.
What you need is Aerostitch.
They're NOT cheap Chinese made Harley crap.
Made in Duluth, by tailors.
Custom fit to you (Like a tuxedo.)
Repairable if you come off your bike.
Durable
Lots of choices of "levels of protection."
Choices of reflective panels and where.
You gets what you pays for.
www.aerostitch.com

Also, more locally to me, there's Motoport.
They do custom tailored suits as well. Kevlar mostly.
Wayne Boyer (the owner) is an old motocross racer.
Very high quality stuff.
Again, NOT cheap.
www.motoport.com

 

This is what I do. I wear scrubs at work - no good for riding, so usually wear my kevlar lined jeans to ride in and then change. I keep a few sets of scrubs and a pair of shoes at work in case I forget to bring a change. I once did surgery all day in my riding boots.

Probably some sort of overpants would work best. I have Tourmaster and they are good and reasonably priced. The only down side is the liner doesn’t come out on the model I have. They are waterproof but get really hot in warmer weather. I keep them in my saddlebag as my rain pants.