What is a comparable modern-day rim to these "fir el 201" rims? I believe they came stock on a 1996 Bianchi Eros.
I need to replace the rims, and I am trying to gauge the quality that I am used to in order to set a baseline in my search.
According to BikePedia, these did not come stock on the Bianchi Eros in either 1996 or 1997. Since this bike came stock with Mirage level components, you're probably looking at a low - mid level quality OEM rim. Fir is/was a good brand, as is Ambrosio (which came stock on this bike). Finding a rim from Velocity or Alex Rims or Mavic just to name a few common manufacturers will provide you with a quality alternative that is affordable and readily available today.
To match the style, you are going to want to get a low profile or "box" style rim as opposed to a deep profile or "aero" rim. All of these companies and more have a style of rim like this.
You will definitely need to purchase new spokes and nipples for this, so make sure you know how to purchase the proper size.