Grado GS1000s will give you lots of space and openness. They are also, IMHO, the MOST comfortable ones on the market--very light on the head and no pressure at all on the sides of your head. They are not bright, but not rolled off a bit like the Senn 650s (also nice phones, I had them and the Grados, but
like the Grados much better). The GS1000s are much less bright than Grados RS1s, which can be fatiguing (I have these too).
The Grados work nice with a last-generation Headroom Max amp (with that nice high frequency filter). They also sound good with a Ray Samuels tube amp (at least they do with a RSA B52).