D750 disappointing colour results

Having had this camera about 4 months after nearly 10 years of a D200 I was told that the difference would be night and day. Well so far I am underwhelmed by the colours it produces. Pretty washed out compared to the D200 with the 18-70 kit lens (when both taken in good daylight of course) I shoot in RAW and use Auto 1 white balance but even in LR 5.7 I can't get satisfactory colour a lot of the time, even with the 50mm 1.8G prime. The stock site I contribute to rejects quite a few on the basis of poor light/colour incorrect white balance. Even boosting vibrance doesn't really help. Here are some examples of rejections on this basis: