I'd try to make room for the corridor monitor if possible since you're using some ETB.
I'd consider Fatesticher to have a tap to untap ability that doesn't require mana.  I should have an extra one because i decided I didn't want to use mine in favour of something cheaper.
Thran Dynammo (or mana vault if you want to spend on a card that should hold it's value well) 
Thousand Year Elixir would be a good fit because you have an untap ability each turn plus give all your creatures haste.


It's a bit of a different direction, but in my land deck i'm playing Trade Routes/Retreat to Coralhelm/(i forget the third card but it's a common articfact creature for 2 mana that lets you tap it to play a land from your hand.   the three cards together give you infinite landfall