Domain Access module with unique menus for subdomains

I'm working with Drupal 6.x for use in a K-12 school district setup with about 30 schools.
Most of the schools have their own custom site already, but for those that don't, I'd like to provide them with an option of having a subdomain on the district site, and I'm experimenting with the Domain Access module to see how that works and potentially fits in.

The menus seem to be the problem there, and from what I'm reading, I'd probably have to handle them differently.

I've been experimenting with this site - http://schooldistrict.edweb.us, if that helps to see where I am (i.e. very new to Drupal).
As a school subsite, I'm experimenting with http://elwood.edweb.us (just setup external DNS for it, so it may take a bit to become active externally.)

I was using the standard Navigation and Primary Links menus, and was looking to use SimpleMenu across the top to replace the Primary Links menu so that I could enable the drodown menus.

When I login as a site author that has access to update the school (i.e. Elwood) site, I add a new page, and assign to a Primary Links menu item, and it also then shows up on the district level (schooldistrict) simplemenu.

I'm looking to keep the menu/navigation links unique to the subsites, which may be either school or district departmental sites, but provide them with an initial pre-defined menu, and leave it up to the school site webmasters to handle menu admin for their sites.

And it's looking like the standard Navigation and Primary/Secondary Links menu pieces won't let me do that - is that correct? I saw 'table pre-fixing' listed as something somebody tried, but it didn't sound like that would help.

I saw mention of a fairly new module - Domain Blocks - that seems like it may have been developed to help with this, and provide theme-specific blocks that can be used for menu links that are specific to a theme.
If this is the case, would I then setup a 'theme' for each school that needs a subdomain site, and pre-setup their menu domain blocks to start with?

Setting up new blocks is still on the 'to learn' list (have this week off, so I'm trying to do a cramcourse learning week in a couple areas.) With blocks, is it reasonable to think a block can provide dropdown menu kind of capabilities that could be easy for a non-techie school webmaster could admin, or does the dropdown piece get deep into the CSS side and is it not something inherent in the way blocks enable additions?

FWIW, these are two departmental sites that they'd like an easier way to update at the district:
http://www.eld.pylusd.org
http://www.gate.pylusd.org
But the menu options/dropdowns may change, and I'd like those controlled by the department after an initial setup/training.
Right now they're using NVU to update, which they find very confusing.
Eventually I'd like to convert the www.pylusd.org site to Drupal, but that's still a ways off - just an fyi, as it shows the obvious difference in theme setups that may be needed between the two.

I still have more checking to do with the 3rd party menu options, but if you have suggestions, helpful tips/info, and recommended ways to go about handling menus that differ between the main site, and Domain Access subdomain sites, all input is welcome and appreciated.

Also, just a note... I looked at the 'SubDomain' module a bit, but it requires the URL rewriting setup.
I'm setting up the server on Windows 2008 web server, and the URL rewriting setup on IIS seems like it may conflict with my application on the server - my application is an asp.net-based application for teacher web sites, which also uses the 404 page, with some scripting, to redirect to the real teacher site with URL params, but lets users use friendly URLs initially. So I'm not sure how these two types of re-directs will work together on IIS, and for what I'm doing, SEO isn't all that important.

Greg