A7 is what I was thinking as well.
Since you're coming from G, you could try this version:
E--
3--
B--2--
G--0--
D--2--
A--0--
E--x--
Because 3rd fret on the high E string will be held down for the G chord, so keeping it held down for the A7 and then moving it down to the 2nd fret for the D chord sounds pretty cool (at least I think it does
).
-tkr