The improved scanning "tooth" on Kodak color films (esp sheet films) does in fact do an excellent job suppressing Newton rings, but not completely if you happen to live in a foggy climate like I do. Films like HP5, FP4, and TMY400 also are good in this respect. But there are a number of downright slick films out there, in which case I find it necessary to use antinewton glass on BOTH sides of the neg. The trick is to
have a very precisely adjusted enlarging setup, and use only as small an f-stop on the enlarging lens as necessary, to keep the depth of field
limited to the emulsion itself. Once you get beyond this basic comment, things get more complicated and require practical testing.