Mind, these are my opinions on your tanks.
72g: too much bottom dwellers; others are ok but you may want to re think your bottom fishes.
20g: that is a lot for a 20. Where are you planning on putting the angels when they are older? Hopefully not the 72g. And the discus? It probably can go in the 72g but I think they prefer to school so that will be a problem. I think the 20 is too small of a footprint for 4 rams. Is this also your quarantine tank?
10g: darios will probably eat some shrimps, even if you have a divider. With a divider, tank will be even smaller for the darios.
28g: don't know about the flounder but if it doesn't get big and eat shrimps, looks fine.
Hopefully this helps you out. I'm just worried about the 20g and 72g because of what I listed. Remember, just don't count the fishes but where they like to swim/rest because you don't want to crowded your tank.
72g: too much bottom dwellers; others are ok but you may want to re think your bottom fishes.
20g: that is a lot for a 20. Where are you planning on putting the angels when they are older? Hopefully not the 72g. And the discus? It probably can go in the 72g but I think they prefer to school so that will be a problem. I think the 20 is too small of a footprint for 4 rams. Is this also your quarantine tank?
10g: darios will probably eat some shrimps, even if you have a divider. With a divider, tank will be even smaller for the darios.
28g: don't know about the flounder but if it doesn't get big and eat shrimps, looks fine.
Hopefully this helps you out. I'm just worried about the 20g and 72g because of what I listed. Remember, just don't count the fishes but where they like to swim/rest because you don't want to crowded your tank.