>>Any advice gratefully received!
>>
>
>Are you sure you need a native application? Have you considered ASP.NET MVC with C#?
>
>It's a really, really nice implementation of MVC and because the interface is a browser, making it tablet/phone compatible is much, much simpler. Not to mention it will work on Mac's too.

Are you sure about the Mac? The architecture is definitely extensible but I didn't know ASP.NET MVC with C# works on the Mac.