Most attorneys charge on an hourly basis for being involved from start to finish on a commercial lease transaction. That said, some will charge a flat fee to do an initial review and provide a list of edits to make the terms more favorable, which your broker would then negotiate. In either case, ask them to prioritize their edits, in order of potential harm to you if the edit isn't accepted, so you can know your downside risk. Confirm (ask for references) that your attorney has experience with your type of lease, as terms of an office lease are different from a retail store, restaurant, etc. Additionally, landlords will be more flexible for a larger tenant (typically 5,000 square feet +) than a smaller one, so if your attorney hands you a list of 30 changes to a 2,000 square foot lease, expect the landlord to tell you to pick your top 10. Finally, it's not typical that the attorney is present at signing. You'll sign, then courier the docs to the landlord for counter-signature.