What we have done is broken the required people into different groups and then customised the views for groups and not individuals...
I know this doesn't help with your specific problem at a user level but have you thought about grouping???
I think I'm one step behind - I can't figure out how to break out maps for a group or a user. The only thing I can do is either let them pick from any map (unacceptable) or they see the same map I pick as administrator (also undesireable).
Do your groups get different maps? If so how'd you do that?
The only way is the one mentioned above - create a view for a user and set the map for him. There is no way to let them choose from only selected set of maps. However, you might combine the custom view with account/view limitations and prevent the users from seeing the nodes that are on the "secret" maps.
As far as I am aware there actually no concept of map authorisation for users. The view restrictions gives the ability to restrict the viewing of individual node items for users. So essentially if you have a map with two types of objects you can restrict some users to only seeing/access the one type.
In relation to maps its not simple. Essentially you will need to create a summary view for each type of "group" or user. Because there is no inbuilt group mechanism you then have to assign say summary view: Helpdesk to all the members of the helpdesk, summary view: Networks to all members in the network team for example.
Remember though that in order to have complete separation you may need to create a separate view hierarchy for every group. This can become a pain if there are similar objects between groups and you need to make alterations as you would have to do it on all the separate maps.