I'm traveling for work in a couple of months and I'm going to have a long layover in Amsterdam. I can be in the RLD between 9am and 3pm. Is it worth it, or is everything going to be dead?

It can be done.
Very few girls are out before 10AM. Some older ones with regulars they see before work.
The Wallen is the closest and largest, but it has been a mess since Covid. Lots of scam artists, and few happy reports.
Singel is an easy walk, and there should be about a dozen choices by 11. No problem providers that I know of, but no stunning 20something girls.
The Pijp is a short subway ride from Centraal, 4 stops, about 12 minutes. A two block walk to the windows from the station at the corner of Albert Cuypstraat and Ferdinand Bolsstraat. By noon, I would expect 15-20 windows to be filled. Girls range in age from 30-50, some are stunning, and skill level is good.
You could set up a meet with an escort. There are some good ones on Kinky.nl. They aren't always easy to get to, so this works better if you know how to get around.

Weasel