Ok so this is what I would suggest
Zebra Eel- Check
Coral beauty-Contingency check
Emperor Angel-Contingency check
Tang-Check
Harlequin-Like you said won't work with the shrimp
Puffer-Contingency Check
Trigger-I say bounce
Heres the contingencies.
With the Emperor, I am not entirely sure that that fish can be housed in it's entirety, in a 150. I am pretty sure they need at least a 180 or 210, as they can get VERY large. With that said it might be more pragmatic to go with the coral beauty, even though they don't really get large, they are a nice fish and quite colorful.
For the Puffer...If you've got the money to spend I would recommend (because you said you wanted color) the Golden puffer. I have heard that they have an amazing personality, similar to the porc, just not as dull as far as coloration goes.
The reason why I said bounce on the trigger is that, you said you wanted to house one for it's life, and when triggers get big they get big. Which made me wonder if there would be any issues with the trigger being a bully to smaller things, especially a zebra eel which doesn't move a lot and doesn't have the aggressiveness to counterbalance that of the trigger's.
So far we have a
Zebra eel.
Coral beauty.
Tang.
Puffer, Possibly a golden.
The butterfly should be ok after reviewing the list.
..................................
Something else I thought of, (and I know you could have some shrimp problems) is a couple colorful Anthias. I know people don't typically add them to FOs' but, they can add extreme color to a tank, especially when the tank matures and you get the nice LR coloration.
That's my 0.02