Free rooms?

This is generally incorrect, because the house will always have an edge on these deals. They know their costs, and they have access to yours, so they will generally win at this game.

I'm not saying you shouldn't take comped rooms. But don't focus on it, because it's a game the house has been playing for a long time, and they're generally good at it.

We always just talk to a host at the Golden Nugget before we check out.
Sometimes all the room charges are comped at the end. Last time all I can get out of them is a free meal, but we didn't play there all that much.
Don't be shy, talk to the host. Just barge right into the office when they are there. It's usually worth checking into.