Negotiating an Offer
That said, there are some time-tested best practices for negotiating consulting offers. No matter how the economy's doing, it is always worth a try. Just make sure you're pleasant and businesslike.
Changing locations after the offer is given is tough. Unless you have a compelling reason for the switch, you may find it difficult to change offices. Your chances are better if you're trying to switch from a more desirable office to an understaffed office.
Whatever the reason, first try explaining the reason for your office change to your recruiting manager and ask that person to look into the switch. They will either tell you no off the bat or look into the transfer. If the person agrees to look into the matter, make sure you both commit to a later date to follow up.
What if your request is turned down? Don't quit there. See if you can find someone in the target office to vouch for the office transfer the higher up (partner or senior manager), the better. When you have found the person, explain your situation, describe why you really want to be a part of that person's office community and ask if there's anything he or she can do. Offer to fly out to the office and meet with the consultants there in person. (If they agree to this, your trip will be worth the money.) This is obviously a different angle to pursue, but it's worth a shot.
In the current economy, it is going to be very difficult to get an employer to start you earlier than your given start date. You would likely be able to negotiate a later start date. The key selling point from your end is that the firm could start paying your salary later than they had planned, which would save the firm money.
Salary and bonus
Getting more money is always tough, especially in a recruiter's market, so don't expect to be able to improve your compensation package. (Just be glad you have one!) The best point of leverage would be to have another job offer in hand that offers more money. You can tell your firm contacts, "I really like your firm best; however, I have to admit that this competing offer is compelling because the salary is $10,000 higher. I'm ready to sign with you if we can make my numbers better. What can you do to improve my compensation package?" If you are an MBA or a lateral hire, you might have another point of negotiation if your previous salary was higher, because then you might be able to convince the employer that you are being undervalued. Do not invent a fake job offer for negotiating leverage.
An MBA with prior consulting experience or lateral hire might be given a first-year associate offer. If you are one of these people, and you feel like you are starting at a lower level than you should be, ask for a shorter initial review cycle, such as after six months instead of one year. This gives you a chance to prove your worth. If you can successfully negotiate for a shorter review period, don't forget to get it in writing; it would be easy for the firm to let this slip through the cracks.
If you don't like the vacation package and the firm won't grant you any more vacation days, ask about the firm's unpaid leave policy. If the firm doesn't have one, get written confirmation (e-mail is fine) that you would be able to take extra days of unpaid vacation. There is no reason why a firm shouldn't be willing to not pay you for a few days a year.
Offer response deadline
Your offer letter will usually have a date listed, stating when you should let HR know you're either coming on board or not. Don't forget to ask for a deadline extension if you need it surprisingly, this often turns out to be negotiable. It's a very common thing to get a little more time to make a decision, so don't feel weird about asking for it.