With the latest version of Muse CC2015.1 you do no see the option to create tablet and phone layout in Plan view of Adobe Muse. If you are not a big fan of Fluid design of Muse and want to stick to the old adaptive layout (To create Phone a tablet layout) manner then you can still do that in Muse.
To create Tablet or Phone layout in Muse Click on Page > Alternate Layout > Select Tablet or Phone.
You will still have the redirection options in site properties.
You also have the ability to create breakpoints in table and phone layouts to ensure that the design fits in all phone and tablet devices.