If you just want a simple dashboard type of UI, you could look into using dashing (http://dashing.io/), which gives you a ready framework to start from. A user over at the SmartThings forum put together a nice dashboard running on a Nexus 7 tablet - https://community.smartthings.com/t/home-automation-dashboard/4926.
Starting with his Github code (https://github.com/FlorianZ/hadashboard) and just substituting for openHAB instead of SmartThings, I have a similar dashboard running off my openHAB server communicating via REST etc.
