Topographical Map of the Catalaunian Plains

[Flavivs Aetivs]

Based on the Euratlas site it looks like they took the Road from Orleans to Sens, then north to Chailey and then East to Morains.

Then they fought on the ridge from Avize to Vertus, which is over 8 kilometers long and could have supported Aetius' Army. It's only 20 klicks from Chalons-en-Champagne too. It looks like there was once a River that ran alongside the road on the south end of the ridge. I would certainly investigate that ridge.

Or they went East to Sens and then East to Troyes, and fought on the Eastern part of that ridge running from North to South. That ridge is over 15 kilometers long, and has a river running along the road on the North side of the ridge.

The Huns themselves, and possibly the Akatziri, were light cavalry, possibly with some lancers. The majority of their subjects were infantrymen, which meant that their army would have been predominately infantry.

EDIT:
Furthermore, Jordanes states:
"The battle field was a plain rising by a sharp slope to a ridge"

The key word there is "A". Attila had retreated to the plains below, hoping the Romans would take to the field on flat ground. However, if you look at the ridge at Avize to Vertus, the area goes gradually up on the west side, and sharply on the east side. The Romans were able to gain the higher ground quicker because they didn't have to march up so steep a slope, and Attila must have been farther away from the ridge when they followed the road to Champagne. The ridge was not two steep sides, it was one steep side, with the plain rising sharply to a ridge, and a gradual side.

I believe the Battle took place 20 kilometers outside Chalons near Avize and Vertus. It is very logical based on the location of the Road, a small stream (it does not seem to exist anymore though), and the steepness of the ridge on the East side (Attila would have faced west in the Battle).