Is there a way to create an openlayers map that adjusts size with an adaptive layout?
Oy. Okay. After poking around even more I found a much, much better solution, and now the whole question seems silly.

When setting up a map to display the data (in Administration >> Structure >> OpenLayers >> Maps), just set map width to "auto." Then it mods all on it's own. One display (block or page), and you don't even need to add any extra css to the container. It just responds. Somehow I completely forgot that auto width was an option when building the map. Super easy!