Best/interesting pair of fish for a 40 gallon breeder. . . A pair that might breed would be cool. . .

[MoshJosh]

All right, so I will be moving soon, and I am planning on setting up a few more tanks, specifically two 40 breeders and two 20 regulars. One of the 40s will be for my SPS (basically transferring my current tank) and both 20s will be for anemones and clowns. . . I thought about doing discus (freshwater) in the other 40. . . But not sure I want to add FW into the mix. . . Any cool ideas for the other 40? I thought trying to pair Pygmy or dwarf angels might be cool but I need to do more research. . . What you guys think? (Coral safe fish is best)