It would be really handy to include not just one menu in a responsive dropdown menu, but also the user login block, the main menu etcetera. Is there a way to do that? I have tried several responsive menu modules, but it seems as though I always end up with several different dropdown menus. I only want one (for all).
You may want to investigate Mega menu options.
I've used OM Maximenu before when I wanted a ton of content on the dropdown: