centerpiece fish

Hello, New to this site, been keeping mixed community fish for over 20 years. Generally tropical south american and different catfish. I am upgrading from a 55 gallon (48" long) to a 150 gallon (66" long..weird dimensions). I've never had a tank this large and have no clue what I'm doing with...

just wondering for future reference. one day I'm gonna make a nicely scaped tank with either some nebula steel or panda guppies and I can't decide on any centerpiece that would look good... also while I'm here- I'm getting some marbled honduran red points eventually...soon...and I'm getting...