Trying to figure out a show from the late 80's or early 90's about a sister and her younger brother, who would travel from their room (maybe through their closet or wall, or maybe a book) and go to a magical land (possibly a forest). They had a dragon friend, but that's all we can remember!

Any help?

Sounds like Dragontales.
Dragon Tales - Official Site (http://www.dragontalestv.com/)