Twenty Twelve Mobile Menu Options for Large Sites?

I’m working on a fairly large website with about 70 pages. I’m in the process of adding more. I have 8 items across my main menu, including Home. On each menu item, but Home, there are several sub pages.

My problem is with the mobile menu: When I shrink the page down or view on mobile devices I get the Menu button. I click on it, I get the 8 pages PLUS all the sub pages in one long terrible list. When you have 70 pages or more, that gets a little messy. No one will want to scroll past 70 links just to get to the content.

Is there any way to make the menu look neater for larger sites with drop down items? Is there possibly a way to hide all the drop down menu items JUST on mobile (I’ve added side navigation as well but the client really wants to have drop down menus on desktop version)? At least doing a drop down and having all the sub pages tabbed over so you know that they are child pages would make a little more sense. Having the menu items drop down on mobile would be ideal.

A few websites that I think make their large websites and drop downs work well with a responsive theme are Starbucks, Disney, Mashable and Microsoft. I’m just trying to figure out how to mimic that sort of concept using this theme, if it’s even possible..

Here is the website I’m working on.