You mention some of the toobs I have.
I would reecomend the mythical realm to everyone, wether you play 1/72 or 28mm. The Minataur you get is slightly bigger then your average 28mm so he can be a runt in 28 or a bruiser in 1/72., the chimera, Phoenix and griffin are slightly small for 28 in my opinion but still useable and Chimera are hard to find.. The Dragon can be used as a baby in both scale. The Unicorn is good for 25mm but would be a Clydsdale in 1/72. Neptune and the mermaid can be used as giants in either scale.Or you can use Neptune as Neptune himself and put the fear of a God into your players.
AS forThe ancient sea life figures, I plan on using some of them as dungeon clean up crew figures. What to do with a giant tribolite and a giant ancient pillbug Im not sure as I have a hard time thinking of a tribolite, even a giant one as a threat.And a giant sponge is even less of a threat, but might use it as an object for a quest. I have a few other toobs so perhaps I can stop by and describe them.