How can I keep certain apps from showing in the command-tab switcher?
If these applications offer the ability to Hide the Dock Item, and live only in the Menu Bar, then they will not show up in the Command+Tab switcher list. Review the preferences within each application to see if this feature is supported.

Last I knew, there were no stable solutions for hiding Dock Icons without adverse application affects.

I have numerous applications that live in the Menu Bar only, and most have an option to show it if necessary:
Alfred, Sparrow, iMenuMeters, Divvy, Last.fm, Flux, Little Snitch, and Tunnelblick.