I've never even listened to the lyrics to see what the Cygnus story is about. Heh.
With regards to 90s albums, definitely get Counterparts and Test For Echo. Their sound after Moving Pictures changed quite a bit for a few albums, but after Hold Your Fire they sort of combined their two styles. More of a straightforward rock sound, without heavy synths, but no more 10 minute prog songs (which they haven't done since Permanent Waves anyway, unless I'm forgetting one).
You won't go wrong with any of the 70s albums, so go crazy with them.