If you want an extensible OS and don't mind getting your hands dirty, maybe you ought to take a look at:https://www.archlinux.org/
There are a lot of very knowledgeable, power-user types who use Linux Mint (in one or more of its flavors) to accomplish what they want. You may, however, be searching for something that gives you a more 'from-the-ground-up' experience. You could also look at:http://www.gentoo.org/
This is sourced based distro that allows true tailoring of the computer experience to your machine of choice. There are distros that have 'spun-off' from the Gentoo base, such as:http://www.sabayon.org/
but that might have more structure built in than you would like.
If my comments are too simplistic for level of linux knowledge, I apologize. Although I am a pretty committed (and biased) Linux Mint user I would be remiss if I didn't suggest that 'your itch might be scratched' by a distro whose underlying philosophy and goals were more directed to the power user and/or developer...
I tend to agree, and am more than willing to learn but because I am more a designer than a coder, I honestly need some hand holding to get me started. I got the feel from the ARCH boards that they don't really tolerate ignorance on any level. So while I love the concept and I think in time with proper help could make what I want using that as a base... it was made clear they would not help ignorant people and instead try and run them off.
LFS, I to would need some hand holding, but if I could get it would defiantly be the way to go. One of the sad problems with Linux is it is hard to find an education for some one who truly wants to do some from scratch tweaks. And most schools teach in practice on windows, maybe OS X if you are lucky, but you are on your won to learn how to adapt that to Linux. When I start to say well I think this should work this way and this would be so much better like this, and haven forbid I say I dont like solution X..... LUGs attack me say I must hate Linux because I don't like their favorite distro, and so on.... honestly this is the first place in a long time where a some what open and frank talk about LInux ant perfect, but the good news is is is OPEN so we can TWEEK, if only we can learn how.
Have not used Gentoo, I thought it was more chose you packages, kind of like ARCH just to a lessor degree, or did I mis understand the project?
What you guys have here is a willing student that has some what IMO are great ideas how to improve the UI/UX of GNU/Linux, and some observation of human factors of "no needs to come like this" so the user embraces it instead of learn to love it (and no I dont mean copy another UI).... But also someone who is ignorant in a lot of ways, probably do not fully understand just how grand and annoying executing those ideas will be. My ignorance has helped me fall so in love with I dont care how much work it is. But it is also keeping me from getting started. And most talented developers do not have the patience to to work with and mentor a noob who has a good idea.