Depends on the use case, but generally right now it goes like this: if it can be done as a high-density Games/Games-like GUI or some kind of interactive media/c

Depends on the use case, but generally right now it goes like this: if it can be done as a high-density Games/Games-like GUI or some kind of interactive media/content display, which 99% of modern apps are: I use MOAI. If it has to be a Business GUI with normal looking things for whatever platform: Haxe. If its a quick tool for lab/workshop: libUI. These approaches all have their pluses/minuses too, of course, but I have found that by exercising platform chops, the workload is minimal once the homework is done. I find it utterly pleasant to code something up in Lua, ship the bins to the devices directly, and see the same thing on every machine. Even between libui and MOAI projects there are chances to share data - i.e. use a lab tool written in libUI to generate content consumed by the game engine... Its like the web, only completely the opposite: you're not targeting someone else app (the web client), but rather running your own client (app).