I played Vegas Dream a lot, but never really got what you might call 'good' at it. So I like to use various tests to check out all of the content that I might have missed.
If you start a new game
And then press
Up, Down, Right, Left, Up, Down, Right, Left, A, B, A, B, B
At the Game Select screen, you'll hear a noise. Then you've got several options at your disposal.
Hold A + B and press Start to enter Message Test Mode
Move the cursor to Blackjack, hold A and press Start to see the ending
Move the cursor to Roulette, hold A and press Start to play the Last Chance Slot Machine
Move the cursor to Slot Machine, hold A and press Start to check out a Face Test
Move the cursor to Keno, hold A and press Start to check out the Sound Test
You'll have to reset the game and to the code again once you get into one of these modes if you want to try out the other ones.