Nice Peace Dollar! I am going to say MS 64. I really like the luster on it and I think that certainly helps the grade. Central devices on the obverse and reverse are faded with wear in my opinion. I see wear on the foremost curls of the head, just right of the cheek line with curls being blended. Reverse central shows blending the feather definition of the eagle. Despite this, luster is good, so I'm going to safely guess 64.
MS-63. The 1921 Peace Dollars were notorious for not striking up all that well due to the high relief, most notably on the hair over Liberty's ear but on the center of the eagle also. @dimeguy that's why you see what said you did.
I'm thinking this is MS64. I'll echo what manny9655 said above: the '21 high relief dollars weren't always struck super well and often look almost, somewhat worn, even when they're truly uncirculated. Aside from the strike, there are a few nicks/contact marks on the fields, enough to maybe warrant MS63; however, the amount of luster surely has to be enough to bump it up to MS64. Edit - forgot to say, absolutely beautiful coin you've got there!
I know these are struck flat (and this one is not as bad as some), but I just can't see MS here. Nice coin, but I'm guessing 55.
It's got enough hits to make me think that it did circulate, but that may not be enough to get it a circulated grade. Since it's a high-relief Peace, we can disregard the flatness at the high points; it just wasn't struck up fully. I think I see enough activity on the cheek to knock it out of MS, but in hand, I'd like to see what the rims look like. (Of course, in hand, I could just see what it says on the slab...)