For large applications, I prefer the all-in-one approach, mapping subs to states/screens.

Only one place to break or upgrade. All states and expected inputs can be known to the program so it's easier to validate correct input between states and also to kick people back to previous screens if there is an error.

Usually, for integrating look and feel, we insert the output from the script into a template page from the site. Usually by having the designer place a special tag within it and this is where the output goes. This way they can change the main layout without program modifications.

-Lee

"To be civilized is to deny one's nature."