There are different strains of this stuff -- all are super-duper contagious, so keep your dogs away from playmates, and if you plan to go visit friends with dogs, wash your hands well and use hand sanitizer. If you go back to the vet, ask ahead of time if they want you to use a separate entrance (I have to take suspected kennel cough fosters through a side entrance into a special exam room, to keep them away from lobby dogs).
The usual thing I hear over and over is healthy dogs usually shake it off in about 5 days, with no medicine. I see that at the shelter where I volunteer, for many breeds.
HOWEVER, I think GSDs have a harder time with it, so I tend to want to put them on Doxy for it, as if it goes bad, it goes really bad (turning quickly into pneumonia, which is sometimes fatal). This isn't just me being paranoid about my dogs -- though a personal experience does emphasize it. (My own male came out of rescue with what I was told was kennel cough in California ten years ago -- upon adoption, a chest Xray by my vet showed it was actually full-blown pneumonia, and he was way sicker than the rescue knew. It took 6 days of vet ICU care, with an IV drip in him, to pull him back to health. He nearly died.)
The GSDs at the public shelter where I volunteer have consistently had a far worse time shaking it off than other breeds. We haven't figured out WHY they are not shaking it off like other breeds, but it has happened so frequently that we know it's not a random fluke -- the shelter has gotten to a point that they are putting GSDs on Doxy as soon as they exhibit the first sign of kennel cough (a runny nose, usually). Before they were doing this, we lost a GSD at the shelter to it last year (it turned into pneumonia very quickly, and by the time he got on antibiotics, it was too late, despite over $1000 in donated vet care and round-the-clock clinical treatment). It's possible the shelter GSDs have a harder time because the breed is so emotional and nearly always gets depressed and then stops eating, which compromises the immune system--and that wouldn't be the same for a dog who gets sick at home. Or it may be that this breed is just more vulnerable, which would be the same for a dog at home. All I know is that I've learned to take kennel cough very seriously in this breed.
I wouldn't give Cipro without talking to your vet first. The antibiotic of choice that I always see prescribed for kennel cough here is Doxycycline -- filling a RX for this costs around $10 at Walmart Pharmacy (your vet can call it in for you, over the weekend, if necessary--talk to her or him before you start trying to experiment with antibiotics in your medicine cabinet). If that doesn't work, your vet may prescribe inhaled medicine.
I personally wouldn't use the robitussin, unless the vet told you to. When I have a foster recovering from this illness, I like to put eucalypus oil in my scented-oil diffuser or in the inhalant compartment of a vaporizer near where the dog sleeps.