Hello and welcome. I think I welcomed you in another thread, too, but now you're twice as welcome.......
...lol.
I run a pet sitting business too and the large breed are the same as the small.........
........other than the poop size, and if they're not leash trained, they can pull you around a bit more. But for me, they're WAY more fun than the little ankle biters. Just plant your feet when they jump on you, and be sure to wear old clothes.
Oh, and be sure to wear pants/shorts with pockets so you can carry around lots of plastic bags.