Answer
All the downtown single deck games have nearly identical rules.
The dealer hits soft 17, and you may double down on any two cards, including soft hands. You may not double after splitting. You may re-split pairs up to 4 hands, you may not resplit aces.*
This applies to single deck games found at the Horseshoe, Lady Luck, Las Vegas Club, Four Queens, El Cortez, Western, and Golden Gate.
I am talking about standard single deck games, not "Super Fun 21."
*The Horseshoe and Four Queens allow re-splitting aces. This is about the only variation beteen different casinos.