You'll have plenty of time to vent personally about your work grievances as you leave, but really, you stand to gain nothing by putting negativity into your resignation letter. And unless you're leaving the state and your current industry, you always run the risk of running into the same people later on. So you're far better off taking the high road and making sure your exit is a classy one.
Prepare for It. Your best option in this scenario is to accept it with dignity and make sure you're ready to leave the office for good when you turn in your resignation letter, whether that means gathering up your personal items or making sure you've collected the names and contact information for the teammates and clients you'd like to stay in touch with.