Using the P mode and setting the My Colors to Vivid will process the pictures you take with the more intense colors. This setting will remain until you change it to something else, such as sepia, b/w, neutral, etc. If the colors are not as intense as you want, you can increase the saturation with the custom colors option. This is described on page 59 of the owners manual. This means that the pictures will not need the extra step of adding more color after you take the shot. You will only need to make this setting change once as long as you stay in the P mode, so I don't see that as too bad an alternative.
By the way, by having all the newer settings for color control, you have much greater control over final outcome of your photos than with the old foliage scene. You can emphasize certain colors to be brighter than others, or even de-emphasize a color to make the other colors stand out more. Try some experimental shots and I think you'll be pleasantly surprised by what you can do with the My Colors option.
