What wings do you find are the best fit for a DP and what you use for a lash ??

The Generic Plastic dragon wings are actually designed to fit the CSM Daemon Prince. If you look at the socket for the vanes on his backpack they fit correctly.
Makes him look big and menacing, though very samey cause everyone's got one.

Try adding plasticard armor to a plastic Balrog if you want something that comes with wings and has a whip already.
Or claim the rock-like skin counts as his 3+.

If it's specifically themed as Slannesh I saw a great conversion which involved adding Belakor's wings and arms from the spawn kit to the boob-snake steed of slannesh (the big one). They go together really well though it takes some modelling to build up some slender shoulders.