Either this is new, or I just wasn't paying attention. In the beginning, I thought that ranges were incompatible with schedules.

http://support.nest.com/customer/portal/articles/178899

Edit: in order to enable this, you have to go through a series of "are you really sure about this?" dialogs on the thermostat -- no way to do it from the web UI. Once ranges are finally set, the UI to program them is exceptionally klunky, but it does work, and now I've got everything set up with ranges rather than just purely heating or purely cooling. You'd perhaps think that the range view might merge the pre-existing heating view and the cooling view, right? Nope. When you enable the range mode, it's a completely separate program; you have to enter everything from scratch.

Sigh.