Take a look at the SwitchStartupProject extension. (I'm the author)
Since version 2.0, it allows you to configure multiple multi-project startup configurations. You can switch between the configurations with a toolbar dropdown box:

To configure two configurations (A, B, C) and (B, C, D):
- Install the extension (you might need to restart VS)
- A new
Startup Project
dropdown box appears to the right of the Start
button.
- Click on it and choose
Configure...
- Select single-project list mode
None
(to hide the single project items from the dropdown)
- Add two configurations and name them
ABC
and BCD
- Add multiple projects to each of the configurations
- Choose the order in which the projects will be started
Note: Unlike the Visual Studio startup projects dialog, the extension does not allow you to choose start without debugging
for a project. So all projects that you add to a multi-project startup configuration are started with debugging.