See, in this scenario, I think negotiation kinda already happened. You gave them a number, they matched/exceeded it. We're not talking about making the second move...it's the third move at least.
Perhaps you shouldn't have thrown a number out there first (the first one to blink loses?), but at this point it's irrelevant.
Me...I have a rough idea of what I want. If the offer is fair, take it. If it's close, tell them so. If they're so far off base it's not even funny, just decline.
And definitely look at the entire picture. I know some people that absolutely demand 100% guaranteed hours (should note that my experience in negotiating contracts is with my wife's contracts as a travel nurse). Either you guarantee all 36 hours per week, or they won't even consider. Or there better be absolutely zero penalty for terminating the contract early. Etc. Me, I try to be more flexible. So, you won't guarantee 36hrs a week, how about 72hrs every two weeks (yes, it's possible they'll say no to 36hrs/wk but yes to 72hrs/2wks). Or perhaps ask for $5/hr more, but agree to be called off once every two weeks. They won't budge on the normal hourly rate, but they'll agree to start overtime at hour 36 and pay a higher rate for that.
Anyways...in this particular case, you gave a salary and they met that. I wouldn't (personally) ask for a higher salary at this point. Perhaps an extra week or two of vacation, a higher 401k match, a company car, a company cellphone, telecommute one day a week, higher overtime pay (if it's an hourly position), etc. No, I wouldn't act like I was greedy, but if it's a job that requires a lot of driving then the company car is a fair request, or if a mobile phone is necessary you can ask for that; if there's lots of busy times followed by slumps then extra vacation time (during the slow times) can actually help productivity, etc.
But that's just me...Mr. stay at home dad who has negotiated some contracts for his wife, but not for himself (I really really need to ask for better working conditions).