I'll go with Nightcrawling in that if you don't already own a corn, they are great snakes, Those were my first snakes and still one of my favorites. They come in uncountable colours and patterns, are easy to take care of, readily take f/t mice and/or rats and stay a nice managable size (3.5- 4 feet).
@Nightcrawler, I don't know where you saw a 7' corn but I think the largest Ive ever heard of was just over 6' and that size is VERY rare. You can except about 4 feet, give or take a few inches
Also Mary made a good suggestion with the Irian Jaya Carpets, they get a nice 4-5 feet, stay slender and are probably the most docile and most managable carpets which are awsome display animals and just fasinating to watch and great to handle!
Good luck with whatever you do choose and let us all know when the time comes