A few more bubble tips

-As long as someone else is alive on the screen, feel free to use the bubble to save yourself from a fall into a hole or near collision with an enemy.

-Bubbles are also immensely useful for getting Star Coins that are out of the way. For coins that may otherwise require a Propeller Suit or Koopa shell, just jump toward the coin and quickly activate the bubble after gathering the coin but before falling into a hole/spikes/enemy.

-Note that collected items (those which can be used on the map screen) will apply to all characters so don't be stingy and feel that you'd be wasting them. One goes a long way.

It's now practically second nature for me and my wife to use the bubble when we've miscalculated a jump or some such.