While it is true that angels only get to 6 inches or so LONG, that's not counting how long those incredibly beautiful fins get... they can be nearly8-9" tall at full size. They prefer a tank with some height so that lovely triangle shape doesn't get squished.
And you are right in thinking that the "fish only grow to their environment" theory is BS... well... a fish might only grow to match their environment, but it's because they die from crowding or are stunted by their own wastes, producing more than the biology of the tank can handle. To put a fish into a tank that is too small for it, you sentence it to an early death.
Angels are cichlids, so they are mean by default. They will eat anything that will fit in their mouths, so the neons and shrimp would be toast in a few months.
To me, your tank sounds well-stocked... I couldn't think of much to add. I would steer away from "flashy" fish because the gouramis are also a little aggressive towards finny or brightly-colored species sometimes. This does depend on the individual fish, however, so your mileage may vary. I've had gouramis that wouldn't hurt a thing, and others that would attack my other fish with reckless abandon....
If your lady truly wants angels, buy her her own tank

Just be sure it's a tall tank, and be prepared to have a houseful of waterboxes before long at all if she likes it
