I see.
I know having a previous knowledge of Java was helpful, but not essential. In my opinion, the most valuable asset I had when learning Alice was a positive attitude. I really wanted to learn how to do visual things with programs, and Java was all I'd worked with prior, so Alice blew my mind. After working with it for a number of years, I felt I'd hit the limit of what I could do in Alice and moved on to something more powerful, more capable of making dreams become visible, tangible reality. Hence, Visual C#, in which I'm able to work with XNA Game Studio (which comes with extensive video tutorials).
My recommendation to teachers using Alice would be to use the exercises in the book to teach students new concepts in Alice, but encourage them to add their own unique touch to each exercise, maybe even creating free-for-all assignments with a goal, but no guidelines (e. g., make a short movie about your dream job). This is what I did myself, and it kept me interested in Alice. I looked forward to expressing myself while learning something I could use in future assignments and projects.
Also, encourage the students to use Alice for more than just your class, if possible. I was able to use Alice worlds for projects in AP English, Pre-Calculus, and for a video in a contest (that I ended up winning

). They should know they're only limited by their imaginations (and by the Mean Queen

).
After learning Alice, you could let them try making something using "java mode," which uses syntax similar to a Java program and is more appropriate for students moving on to something more orthodox. After that, its up to the teacher. If you want to stick with easy languages, go with Python (this will come with the added bonus of advanced students being able to write custom scripts in Alice to accomplish tasks such as saving and loading game-specific data). If you want to move on to something more mainstream, Visual C# is a good choice because of its ability to use more powerful graphics drivers than Alice, its ability to load and unload data as modern games can (unlike Alice), and its video tutorials for beginners covering both 2d and 3d gaming (for XNA Game Studio, at least).
There. I did my best to answer each issue. Hope it's not too much to handle. May the teaching go well!