If it has to match the décor, possibly you could give a hint as to what it is, so the suggestions won't be too silly.
The alternative is to change the décor to suit the picture... Now I must admit, the suggestion is a bit extreme, but do you feel the
need to redecorate? If so, this could be the excuse you're looking for.
As a general feeling, I think you should go for the DMC satin effect Turquoise (S995 or failing that standard 996 or 3846). Beautiful vibrant colour, and it won't be too bright -
everything else just looks a bit dull next to it. I always use this thread for my signatures on my pieces, as it's the closest thread colour to my favourite fountain pen ink I can find, Pelikan 4001 Turquoise. Some of the light effects ones might be good. How about DMC E825, Sapphire Blue
http://www.cross-stitch-heaven.co.uk/e- ... 1389-p.asp? It's darker than Royal Blue, but the light effects will make it have impact.
Regards,
Richard