What language to use and whether or not to bother with cross-platform compatibility?

I mostly use macs and am interested in writing desktop applications & command line utilities. I will not be distributing them via the Mac App Store since they will not work correctly within the "App Sandbox". Using a mac, the first choice that comes to mind is using Xcode/AppCode and Objective-C and sticking within the Apple ecosystem. It seems that there are plenty of companies who focus on just Apple compatible software and have no issues finding users/buyers. But, I am also very interested in C/C++ and wxWidgets/Boost etc, which would allow the applications and utilities to be cross-platform, and possible get more use/interaction/contributions from a wider audience. I am not interested in using Java/Swing or ruby/python/whatever other language. I'd like to stick with C based languages (C/C++/Objective-C).

So which route would you choose and why?