Cheapskate that I am, I usually do Hyatt (Globalist), Marriott (Plat), or IC (Amb) if I need to checkout very late, sometimes asking if I can use the lounge for another hour or two after 4 PM.
Anyways, out of curiosity, do you just earn extra points or an extra night if you pay (i) 50% extra until 6 PM or (ii) 100% extra to stay until 8 PM, 9 PM, or whatever?