Johnny, I remember several years ago, after learning a couple of nice-sounding tunes in open-G (DGDGBD), I sought to keep my acoustic tuned that way exclusively; but after a while I found that the "vibe", if you will, of the tuning started to become somewhat over-familiar (does that make sense?) and therefore a little monotonous. So I then discovered a few tunes in DADGAD and became enthusiastic about that tuning, but the same thing eventually happened-- it has a certain "sameness" to it that made me grow a little restless for a different sound. Then I heard some Tommy Emmanuel tunes, and read an article about him in which he said that he uses standard tuning but that he often employs little variations in his chord voicings to make it sound as if he's using an altered tuning of some sort. I think Tommy does in fact utilize drop-D with some frequency. So, it may be that standard tuning, with the occasional dropping of the 6th string down to D, may be a very good way to approach things. It's worth noting that one of the things that the DGDGBD and DADGAD tunings have in common is that 6th string dropped down to D; so perhaps one could say that standard tuning, with a dropped-down 6th string, gives us the best of both worlds.