Tom,

the trick with menu systems is to structure them as far as possible.

i.e.
if you are in a menu to set the clock you don't want to see an item "set LCD contrast", do you ?

A good example are mobile phones

You might remember the early motorola phones:
it was almost impossible to change anything without having the manual next to you.

Today (with almost any phone) you can do everything with only two or three buttons without having had a look at the manual at all.

What I'm trying to say is:
The work starts ways before you start writing your first line of code.