Ahh great news on the whiptails! Fantastic fish. I'd love a green royal one day. Fascinating fish, so distinctive and majestic when mature. I second the angels have to go, and i see your planning on them leaving which is good for the discus. I can see why you'd have both, it seems like a good idea, but concidering the discus are always going to be concidered the kings/queens of the tank the angels will always steal your attention.
Vallis in general is a fantastic plant. It grows so readily, and spreads so well it quickly fills out a tank. Always in a 'natural' manner also. I've found mine always spread around and never in straight lines which was great. Giant Vallis is certainly a looker. Have you thought about getting a group of them? Something i've always wanted to do, but with it being so big i've never had a tank quite big enough to try it.