I'm going to go against the tide and say that CE is *just* about worth it (perhaps more for ZRH than LCA). The difference in Avios (and the extra £ for RFS), in my opinion, isn't huge and is more than made up for with the (albeit somewhat minor) perks you get with CE. The last time I flew on the 767 was on LHR-ARN and it was a splendid little flight with a fun crew in CE. The BA 767s won't be around for much longer so I would definitely experience them in "style" (or as much style as is possible with CE).
Of course, none of the options compare with the 777 doing the runs on the LHR-MAD route this summer.