I recall being able to compare regions of Ce and Cbn genomes via a “synteny viewer” - is this still available?
no, we removed that a while ago, as the we had problems with the underlying infrastructure and data.
But Hiram Clawson did some work at UCSC with whole genome alignments as part of the N-genome publication (I believe it was based on WS223 or so).
And we put up pairwise alignments at EnsEMBL-Genomes based on TBLATN and LASTZ (based on WS230 for C.briggsae and WS235 for C.elegans).
In EG they are buried in the location → region comparison → then hit configure → select species
At UCSC I can currently only see the chains and nets, but I am sure they had more.