Whatever you do, never put your laptop on the floor for takeoff.

I was in a bulkhead E+ middle seat a couple of weeks ago, the guy by the window was trying to figure out where to put his laptop and seriously tried to put it on the floor. I told him it's not a good idea (very dumb idea).

I don't see why one would need to have the laptop accessible when takeoff while in a 757 lie flat, since you can easily get up and get the laptop from overhead bin after takeoff.