I feel like you could lean in harder to the 'tap my creatures and do stuff" effects if you wanted to?

• Adarkar Valkyrie is hilarious as you can use it to get your opponent's creatures back when they die. And if he's indestructible when he's tapped, all the better for you!
• Droning Bureaucrats is a funny political card. You could use it to your benefit or one of your opponents attacking another one of your opponents.
• Devout Invocation would be on theme here.
• Drumbellower would be fun and allow you to retap/crew every turn - or keep things tapped by just re-crewing.
• Field Surgeon (or Hair-Strung Koto allow you to keep unlimited creatures tapped with either damage protection or milling ops.
• Flight-Deck Coordinator gains life for tapped creatures and Chrome Companion or Compassionate Healer would be on theme here too.
• Hand of Justice because - who uses Fallen Empires(?) and creature destruction!
• Orphans of the Wheat gives you a way to tap all your creatures. And with Rogue's Passage...
• Rinoa, Angel Wing would be good recursion for your stuff.
• Sword of the Paruns also pumps your tapped creatures
• Endbringer is good utility on many fronts.

Maybe some more protection too like Ghostly Prison or Norn's Annex?

If you decided to go with more legendary creatures Relic of Legends could be funny as it would simultaneously ramp and allow you to keep most things tapped!

Thanks for the upvote! If you have any suggestions on any of my decks would love to hear them!