I use a Topeak rear rack. I switched from a standard rack to one with a 2nd set of lower rails precisely because some panniers sat higher than the platform, which meant anything on the platform had to be narrow enough to fit between the panniers. For that reason, I think it's definitely worthwhile to go with the 2nd set of rails. To me the lower rails are more important than platform width because as long as the panniers sit low enough, other items can overhang the platform, and sometimes the pannier tops can create an extra wide surface to store other gear.

Also, for the front rack I use an Old Man Mountain Cold Springs rack. Has a platform and a lower set of rails (which may not work with all panniers, but they work with mine), and it's aluminum, so it may be lighter than a lot of other options.