Given your preference for Omega (of which I very much share), a fantastic addition would be a Dark Side of the Moon Apollo 8 (311.92.44.30.01.001) Speedmaster. Complements your existing speedmaster while also being totally different.
Would also highly recommend a Zenith Chronomaster Sport (03.3100.3600/69.M3100). Would be a great piece with a unique 1/10th second hand complication.
I totally identify with this. My father would freak about my speedmaster even with being able to afford it. It’s just against our midwestern budget DNA.