I've been thinking recently that I need to learn something new. Whether it be a new technology on the .NET side of the house, or a new language, or a new web framework. I'm not sure what, but, I definitely feel like I need something new that will cause me to stretch my mind a bit.

I've had the itch to dive into WPF for a while, but don't have a whole lot of time at the moment to do anything on that front.  While I do have several ideas for little WPF apps I'd like to see built for myself I have concerns it'd be a wasted effort since my design/UI skills have diminished over the years, and what sense is building a WPF app if you can make it look slick as all get out? 

I've also been thinking a bit about trying my hand with a new language.  The top contenders would be Ruby, via Rails, or Python (with IronPython).  I'm leaning more towards the Ruby/Rails track since it would involve me stepping almost completely out of my comfort zone. 

I have a few things on my plate that I could choose to do using non .NET technologies.  Of course the problem is that I could undoubtedly do them much faster using my bread and butter technologies.  The benefit of the .NET appraoch would be that I could get more things done and perhaps have extra spending money due to being able to do more of the little projects I've been asked by peeps to lend a hand on.  The downside is that I'd still feel like I need to learn something new, and stretch my brain a bit.  I've run into this same scenario many many times in the past, and always went with the approach that would get things done the fastest since I never seem to have enough time available for anything else.  The problem, of course, is one of the main reasons for doing little side projects outside of work is to stretch yourself in ways that you might not be able to otherwise.

When confronted with such dilema's how do you choose?  Do you go safe, and stick with what you know, or do go with the more difficult, and potentially more rewarding path of trying something completely new?