There were some issues back in 10.2 days about some peeps FP's screens not waking up, but no probs with 10.3.x Sleep is your friend, you can either do it while logged in or if you want more security you can do it from the login window.. Anecdotal evidence suggests its better to sleep a computer and keep the bits warm to extend the life of the computer rather than powering up and down all the time and the heat changes that causes. Plus you dont have to wait till it boots up
Sleep man !
Edit - I look after 3 FP's and they all sleep in various degrees of state (screen, totally etc), not a prob at all..