As I think about the two words, I regard minimalism as simplicity taken to an extreme.
As for which word is better, that's probably simplicity. Minimalism suggests that something might be regarded as overly bare, however, which is why I think simplicity is a better option most of the time. Still, this is highly dependent on context.
I like simplicity in website design. It connotes easy-to-navigate web pages, free from unnecessary clutter.
I appreciate minimalism in a site intended to be accessed from a mobile device. It shows the website's developers are sensitive to the fact that I might have a quota for the amount of data I access.
As a side note, I concur with what jwpat7 said above: I don't think you want to use the words play around. You could use experiment with (or, more informally, dabble in) if you this is something you do only on occasion. On the other hand, if these are design principles that you strive for as a general rule, you could say, "My goal is to infuse elegant simplicity into every webpage," or something like that.