i'd definitely look into a Banana/Coral Glow Pastel combo, that would be a great compliment to what you're already working with (note: i friggin' love the CG/Banana gene so i may be biased). i'd really consider getting a 0.1 Piebald combo: expensive but will make an awesome addition.
alternate route: since you've got plenty of time before your snakes are even mature, i'd say start saving your pennies and wait until you can get something killer like a 0.1 Banana/Coral Glow Pastel + ??? Piebald. that way it's less animals and more genes to work with. this, of course, is easier said than done; trust me, i know!