Blackjack Promotion and Blackjack Research

Promotion of Blackjack

House advantage (approximate, may vary with different rules)
Without basic strategy 7% average.
With basic strategy 0.5% or less.
Card counting can reverse the advantage up to 1% to the player.

blackjack promotion
Using different number of decks: all other conditions being the same, as a general rule the fewer the decks, the better for the player.

Allowing the dealer to hit a soft 17: a disadvantage to the player. It gives the dealer a chance to improve.
Allowing a double down after splitting pairs: can be advantageous to the player if used wisely.
Allowing re-splitting of Aces: a clear advantage to the player.