I wear Tourmaster Venture Air overpants, and they are extremely convenient. Side zips go up higher than your knee, can have them off in about a minute without removing your shoes. They have knee and hip pads, heavier cordora in knees and butt, and come with an insulated liner and a rain liner also. I've had them for years, and they've help up very well. Just starting to get some pilling on the mesh, but no complaints considering their price point and how many times I've taken them on and off. I commute all summer in them.
That said, I've never felt comfortable wearing shorts under a polyester based mesh pant, for fear of it melting into my skin in a slide. I wear some type of cotton layer underneath, and hope for the best. Plenty of other people wear shorts under them, so I suppose it depends on your risk tolerance. I think they make a version that isn't mesh too, so if you don't mind being a little warm, thats an option. In my opinion the key with overpants is that they are easy to take on and off without needing to take your boots/shoes off.....these are great in that regard.
If money is no object, Motoport kevlar mesh overpants would be my choice. I would feel comfortable wearing those over shorts.
'79 Yamaha XS650