Nirvana's approach (which seems to have also inspired GTDNext) is quite good, one of the two best approaches. I would call it a tag based approach. The Areas are essentially a kind of tag, but these tags are connected to a global on/off switch that allows you to hide entire Areas from view.

The other very good approach is what I would call the hierarchical approach. This is what Doit and Omnifocs have. Omnifocus calls it "Folders". Doit calls it "Goals". In both cases these Folders aka Goals serve as top-level containers for a bunch of related projects.

Personally I feel no need or desire for Doit to change from a hierarchical approach to a tag-based approach. I actually prefer the hierarchical approach. But it is necessary to complement the functionality in several ways. As it is now the Goals have almost no function at all. For the Goals to become useful. you would need to be able to filter by Goal, group your lists by Goal, see all tasks within a Goal (as if it were a big super-project), and even (for many people, but not me) be able to "hard set" the entire scope of the app to just one or a few selected Goals that you want to have visible when you work and then change the scope when you get off work.

I keep in the service business and personal affairs and projects and big problem for me to share them. Do it with the help of goals or tags - very uncomfortable.

I think I probably did not express myself clearly. I totally agree that more functionality is needed. No question about that.

What I am saying is that Nirvana's approach IS in fact a "tag" based approach, not a hierarchical approach like Doit's or Omnifocus's. Both a hierarchical approach and a tag based approach can accomplish what you need, but only if the full functionality is there. For example, many people need to shut out all the Personal things while at work, and vice versa - just like you do. As it is now, neither Doit's Tags nor Doit's Goals can do that for you. People who come from Omnifocus or Nirvana often complain, perfectly legitimately, that this is not possible in Doit.

If Doit were to implement Areas in a tag based way, like in Nirvana, they would have to make the tags inheritable, such that tasks can be grouped by the area tag of the parent project, and the area tags would need to be associated with a "sticky" on/off selection switch, and the tags would need to be visible in the list (which they need to be anyway, if they are to be of any trusted use). If Doit were to implement Areas hierarchically, using the Goals feature, they would have to enhance the Goals feature in the ways I outlined above.

Both ways will work. I personally prefer the hierarchical way as it inherently gives me a clearer overview when I review my stuff without me even having to filter or narrow it down. Others prefer the tag approach as it allows them to put a project in more than one area, which is something i would never dream of as I want to keep my area definitions very sharp.

+1

Conveniently when the Areas is not only multiple and nested

Example:

Private
Family
Sport,
Health,
Outside interest

Work →
Full time,
Freelace,
Learning

When choosing a parent Area shows tasks and projects that belong to nested Areas

Screenshort http://dl2.joxi.net/drive/0001/1507/83427/150216/dd9d8093cf.jpg