The only issue with "walking around at night" is that Orlando isn't really a "walkable town." If you just mean taking the dog out at night, most of the suburbs are fine. Basically, stay out of the west side (Paramore, Pine Hills, and Metro West soon) the northeast side of Sanford. There also is a fair amount of crime right around UCF simply because there are lots of targets (students). I think the Seminole County suggestions (Altamonte, Lake Mary if you can afford it, parts of Winter Springs) are pretty good ones.