Does the cake have to be iced? If you're using fall colours for your October wedding and if the cake is pretty without icing, let it stand on it's own with a few richly coloured flowers for adornment - red, yellow, orange, ivory. You can also add ribbons in complementing colours if you wish.

If the room will be in low light, you can opt for a dusting of sparkle sugar (don't know what the stuff is called but it has a soft sparkly-glitter effect on cakes) and some well placed candles and that will make a beautiful presentation, too.