I would not use Stanley Steamer. We used them twice and in both cases the carpet seemed to get dirty again very quickly. Within a month, the carpet appeared as dirty as it was before they cleaned it. We kept off the carpet after cleaning for days. I realize the SS franchises are different and it will depend on the skill of the folks actually doing the work.
We plan to try using the Chem Dry folks when we have it done again. Their process is claimed to be better using less water which allows faster drying of the carpet.