As far as keyboard/mouse go, I use the built-in KVM with my Dell 49" monitor and a PC/Mac plugged in. It works very well--but switching is not as seamless as Flow-compatible hardware (you have to press a button twice to switch from Mac to PC; but there is a hotkey switch from Windows to Mac).
I have also used a Flow-compatible Logitech keyboard and mouse combo (MX3 series). Also works well, but the keyboard switching was not as reliable (i.e., had to confirm often that it had indeed switched by simply moving the mouse cursor).