With kids after a long flight and midnight arrival, the hassle free option sounds like a pretty good idea. 3 minute walk down a hallway from the arrivals hall and you're at the Regal. However, it is somewhat run down and clearly the worse of the two hotels. So it really is a decision of convenience vs. quality.
If you have to get up at 8 am the next day anyhow, go for the Regal. If not, I would suck up the short transit and stay at the Marriott.