If you come during the tourist season (memorial day to labor day) exspect to pay high prices for hotel and motels. Watch out for the first full week in August too, it is the Sturgis Bike Ralley and all hotels are usually booked solid.
I've lived in Rapid City for 13 years and I personally don't appreciate the blatent lies people write about my town. Stock Show riots? Closest thing to a riot I've ever seen at the stock show was when a bull got loose last year and ran up Omaha St. Illegal aliens on street corners? They make it sound like there's roaming groups of marauding immigrants, which there isn't, and 45,000 illegals seems to be a completely fictional number to me. And as far as the "bad weather"... 12 feet of snow, no sun for weeks at a time? This ain't Alaska by any means, I'll agree the weather is a bit strange at times, but over the past few years I haven't even been able to go snowboarding during the mild winters. "If you don't like cowboys and western stuff, you will probably not find too much to do in Rapid City"... not true. I'm not a cowboy, I don't particularly care for the whole "western" theme, but I still manage to find all sorts of stuff to do in Rapid City and around the Hills. I've been here 13 years, and there's still stuff that I want to do that I haven't been able to yet.
Of course there are a few of the tips that are actually valid. Such as the "Rapid City Homeless" tip, I've had run-ins with the type of people this tip is talking about and fully agree. The tip stating stay away in early August... unless you really like motorcycles and the culture associated with it, you should probably keep your distance. The mayor was arrested for disorderly conduct (personally I found this to be hilarious), but seriously who hasn't had a little too much to drink and got a little stupid. Still not nessecarily behavior becoming a mayor, but he's not mayor anymore either.
So over all, most of these "Warning Or Danger" tips are completely bunk. Rapid City is a beautiful city with many things to see and do with a minimal of danger involved.
South Dakota is a very beautiful state. Scenery is breath-taking. But BEWARE! They are at times curvy, 'can't see around this bend', kinda roads. Many deers and other animals in the road. As you drive, you see tons of signs saying 'Watch for falling rocks'.