I play alot of open D and find it very versitile... Using a capo on the 2nd fret gets you to E but for performing, if I only have one geetar, G is a kinder open tunin' 'cause you can tune yer A string back up to A and now yer in a "Double Dropped D" tunin', which ain't exactly like an open tuning 'cause you do have to chord it but has that nice modal sound to it and easy to get back to G, which BTW is an A if you capo to the 2nd fret...

Just MO...

B~

Oh yeah, I haven't played standard tuning in years but having played it for 30 or so years I still have it all imprinted...