Eames 670 and 671. Real? Grain structure?  

Looks good to me. And in very good condition, too. The darker streaks in the veneer are not a defect, per se, but for 3 grand you could probably find another if they bother you.

As tktoo said, the dark streaks are not a defect, but just something that you often see with bookmatched veneer. The headrest of the chair in this image is veneered with four strips of veneer cut from the same block, with each sequential one being flipped over to serve as the mirror of the other (yellow arrows show the seams). It creates a pattern that is sometimes quite pronounced, and other times less so, depending on the pattern in the piece of wood use for the chair. It could be that older eames lounge chairs used wider pieces of wood, so fewer individual veneer pieces were used on each shell of the chair.  I would actually be curious to know if there are any older eames rosewood lounge chairs out there with single pieces of veneer being used on each shell.
 

Thanks for the replies guys. Makes me feel much more confident in the purchase.
I'm not really bothered by the marks (in fact, I like how it makes the chair distinct). Just was scared it was from some issue the original owner may have had.
Seller is asking $3200, but she said there was some wiggle room in the price. I'm hoping to get her down to $3000.
Is this a good buy? New ones are starting at $4800 now and I just can't see how buying a new one could justify my spending the extra $1800 (not to mention the $300-400 in tax).
I'm also unclear as to the wood/leather combo (Walnut/Black?) and the year.
Thanks for all your help! I love that I discovered this forum. It's wonderful.
 

It's been awhile since I've shopped for one, but even a dozen years ago $3K seemed to be the going retail for a good set. The one in your pics is rosewood and perhaps a tad faded. More likely it started out lighter in color as suggested by its overall even coloration. The rosewood they used back then was highly variable in both color and grain figure. Sometimes more wildly figured examples can command a higher price.
IMO, vintage sets are always more desirable and the one you've shown us displays features I like. Particularly the squared-off arm pads, darkened panel edges, broken-in cushions, and the je-ne-sais-quoi that a well-loved and cared for vintage example exudes. I'd buy it.

Hey Guys
Just wanted to update.
I ended up buying the chair and it is currently being cleaned (sanded and re-lacquered?) and having it's brittle old dry shockmounts replaced by David at Comfort Upholstory here in Chicago.
Will post pics when it's arrived back!
 
Thanks to TKTOO and TCHP for all your help!
 

Congrats on the purchase and the decision to clean it up and replace shock mounts. I'd like to add that the chair is probably from the 60's as suggested by the round black medallion. Normally around that time period, the cushions would be filled with down and feather or a mix of down and foam. What filling does yours have? 
Also, when you said it's being lacquered, did you mean being oiled? My understanding is older production had mostly oil fonishes whereas the new ones have lacquer. Excited for you!!

Hmmmm
Well, I found a piece of paper inside, under the cushion, from when the chair was bought. I belive it was a mix of down and duck feathers. Not sure about the foam. I'll have to check it when it gets back, but seeing these little pieces of paper was really cool. Didn't expect to find them under there.
I believe the chair is from the mid/late 70's (according to the original owners daughter).
As for the lacquer vs oil question, I talked to the guy restoring it. He seems to know what he's talking about and I've seen countless Eames chairs he's restored for display at museums and galleries here in Chicago. He was also recommended to me by an awesome vintage shop and apparently he does work for the Mies van der Rohe society here in the city.
He told me that lacquer is the what this chair needs when I asked what kind of oil he was going to use. I didn't understand everything he said to me in that I'm no furniture expert, but apparently, if he were to just oil the chair, it wouldn't do much for bringing back it's original luster for very long? He said it would dry out in a matter of weeks and originally these chairs had a lacquer on them? Maybe I'm not using the correct words here.
By the end of the conversation, he assured me, the chair would be lightly restored and look like it originally did coming out of the factory so many years ago. He's bring it back to it's original state and the shockmounts would be replaced and wouldn't have to be terrified about sitting it.
I suppose I put my trust (chair) in his hands. Hopefully it works out : /
***EDIT***
From the Herman Miller store in reference to the new chairs being sold:
"We are reviving an oiled finish for two of the available wood veneers—walnut and santos palisander that closely match the look and feel of the finish used on the original chair and ottoman. Just like the original oiled finish, it will need to be maintained with periodic hand oiling.
You can also choose the standard, high-performance lacquered finish, which requires nothing more than dusting."
I'm assuming my chair was orignally lacquered (being from the 1970's). This is why he told me it is not an oiled finish. It is a lacquered one (Wipes sweat from brow).