If this was a Y/J ticket, and you have no UA status, you will get $200
If this was a J ticket, and you have status, you will get $500.
Now, I dont understand why you just sat around, why did you not call United from the lounge via Skype???
Why didnt you spend the time actively looking for connections that YOU found acceptable, instead of relying on United agents, who will of course rebook you on what suits them. If you were proactive and demanded being rebooked on SQ - they would have had to accommodate you.
Bottom line is you booked transport from A to B - and thats what you got - perceived "quality" of airline doesnt really matter here - but if you wanted to be rebooked on SQ - you should have presented the agents with that option, and not accept the other - when there is a delay - you are in total control - and UA has always been more than accomodating in these situations, even changing the destination.
Silver lining - you probably got rebooked in revenue classes, and will earn mileage.