"It should be obvious why suspend's only your upkeep."
Obvious huh? You 'obviously' missed a subtle difference. Future Cast places the card into play (can happen during opponents turn) where as w/ Suspend the spell must be cast.
How about a mechanic that allows an alternate casting cost that places a card into play after x number of turns?
W,Future Cast 3
(Remove Rift Warrior from the game with 3 time counters on it. At the beginning of each players upkeep remove a time counter. When Rift Warrior has no time counters, put it into play.)
Sabotage 3 (Target opponent creates a 0/0 colorless Trojan artifact creature token with 3 +1/+1 counters. At the end of its controller turn, remove a +1/+1 from this creature. When this creature dies it deals 3 damage to it's controller.)
This allows Sabotage to be placed on non-creatures as well.