Verbal negotiations are normal and common sense. Just make sure it finds its way into your contract. Because remember this... contracts have the employer's as well as the hospital's best interests in mind...not yours. EVERY TIME.
I had a job offer with a verbal contract for a sign on bonus straight out of residency. I didn't read the contract very well and thought the new boss was good for it. It wasn't that I was being greedy you understand, I just literally had NO cash to move cross country my friend. Well, long story short... they reneged on the sign on. I threatened to back out and the guy who until this point had been the absolute nicest individual I had ever met proceeds to explode over the phone in classic Mr. Hyde style and threaten me every way from Sunday. Well, then I was really pissed and did back out.
Next job, I hired an attorney to review my contract. We negotiated a little bit and settled on something both of us could be happy with and I totally recommend doing that. I've had an attorney review most of my contracts since then though the CMG contracts are easier to read and negotiate yourself once you've seen a few of them (thought I would still recommend an attorney to review).
The problem lies in relying on your attorney to negotiate every recommended change which usually is a bit over kill. You don't want to be that employee with a million requests and bottled Fuji water on every shift. You have to become a little savvy with figuring out which things are important and which aren't... Not all attorney's are familiar with what items are important to physicians and which ones...just aren't really a big deal nor worth negotiating to have changed.
Sign ons, malpractice, tail, minimum guaranteed shifts, non compete clauses, indemnification clauses, termination clauses, compensation, etc..