A corn snake, just about any of the N American rats, and most kings would fit your needs.
Just figure out what size you want and what colors you like and go from there.
The corns have sooo many morphs right now, and the rat snakes are getting quite a few as well! The king with the most color and pattern morphs would have to be the california king. But, dont let that sway you. Most of the kings and rats have the same requirements and do well in a rack system, provided the plastic tubs you use are big enough for the snake at adulthood.
Do some surfing on the various breeders who have links here on kingsnake and you will find what you want. But be forewarned, snakes are wayyy addicting!!! You wont stop at just one, Id be willing to bet on it!! LOL
My Dwight Good stock albino black rat.

-----
1.0 Corn snake
1.0 Black rat snake
1.0 Albino Black rat snake
1.0 Everglades rat snake
0.1 Yellow rat snake
1.1 California king snake
1.0 Prairie king snake
0.1 Black king snake
Good luck and Happy Herping
Brian