We have several applications with the requirement to separate the API from the UI to support Desktop, Mobile and web platforms. Generally you want to keep as much of your business logic in the API's and leave the UI's as "window dressing".
Here's an example project layout (simplified a bit):
ProjectA
Lately, my team has been using WebStorm for the UI stuff and Visual Studio for the backend stuff and the result has been fantastic. Separating the development environments helps keep you in a certain "head space" while you're working.
I build things that go *splonk*