How can I have one layout for landscape and one for portrait? I want to assume extra width and conserve vertical space when the user rotates the phone over sideways.
By default, the layouts in
/res/layout are applied to both portrait and landscape.
If you have for example
you can add a new folder
main.xml into it and make the needed adjustments.
See also http://www.androidpeople.com/android-portrait-amp-landscape-differeent-layouts and http://www.devx.com/wireless/Article/40792/1954 for some more options.
In the current version of Android Studio (v1.0.2) you can simply add a landscape layout by clicking on the button in the visual editor shown in the screenshot below. Select "Create Landscape Variation"