I don't keep big snakes but I research them. I would recommend a Burmese; they're not as fast or long. Burms get to be 10-15 feet for the males and can reach upper 20s for the females, but usually females are 15-20 feet. Retics are pretty much the same, just a little longer. Tics are really fast and inquisitive, matched with intelligence this makes a difficult animal. Burms are slower and not as bright, but they get a lot fatter. Overall, a Burm is a good first step into the realm of giant snakes.