Rosy boas are a great first snake, and come in many attractive colors. They stay small, are easy to care for, and usually have a good temperment. They don't need high humidity, in fact, too much humidity can negatively affect them, as they are a desert species. They do well in either a naturalistic, display setup or something more utilitarian. If bright colors are important to your friend, there are several lines of albino which display bright orange color, as well as several Baja localities with deep red color.
Here is one of my breeding males, so you can see how bright they can be:
He is a Harquahala locality albino. This is the desert subspecies, which stays pretty small.