Unless you're in a market with very scant tenant demand, the landlord usually drives the leasing process. After all, you're looking to occupy his building and if you can't meet his terms, he can lease the space to someone else. The best way to mitigate this imbalance is to have negotiations going with multiple landlords at once. This not only lets you choose the best offer but also negotiate more aggressively to get a landlord down to his best offer, knowing that you have alternate options waiting.