My friend who just built a house in Aledo has her entire house floored with stained concrete. I used her "stain" man to recently have my front and back porch concrete stained and was pleased with the job. It is very easy to sweep and mop to clean. I preferred to have no "grout" lines or etching, however , my friend's house has all kinds of great patterns in hers (cobble stone in bathroom, brick look in kitchen, wood floor look in her study, and plain without etching in the living room).
Stained FX is the name of the company and Brad Sosbee is the owner. He came over to my house in FW a day or so after I called to give me a free estimate. Very nice guy and knowlegable. I will say though that he had his "crew guys" come over and start the project. They were pretty sloppy so Brad had to come over and clean up the areas they stained that were not supposed to be. Brad kept coming over to tweak the job untill I was satisfied. He sealed the porch a day or so after the stain had dried. So, if you call him I would recommend that HE actually do the job. Be patient and wait for him to become available - it is worth it and really saves time "redoing" someone else's not so good job.
I can't find his number right now, but I'm sure it is in the phonebook under Stained FX.
Best of luck! I think your idea of staining a room that the kids and dogs use is right on target. If you have concrete under that carpet, by all means take the cheapest easiest route and get it stained.