Pleased you are going for it Allan, I'm sure you will be chuffed to bits with the results.
As for the sales guy saying it will not add to any reasale value is utter nonsense - providing you stick with something tasteful colourwise and avoid the motifs - sorry.
Also my advice would be to steer clear of the ruched type leather which is best suited to the larger luxury motors.
My choice for
NHB would be Black bolsters, arm/head rests & door cards with perforated facings in a maroon type red. Contrast stitching in silver.
Purely subjective, after all it is down to personal choice.
Looking forward to seeing pics of your results posted.