play decree of justice.
you can cycle under a standstill which is awesome.
You may also think about StP.
And my personal thought is that Wastelands can never work in 3 Color deck.
There is a slew of tournament results around right now where GermBus Keeper is dominating the top spots, a 4-Color Control deck that packs the full 5 Strip Mine effects. There have been others in the past as well.
About your deck- have you considered simply dropping red in favor of white, and going the weenie route with Meddling Mages obviously, and possibly some other decent White Weenies?
I think if you add Decree of Justice as Agressive Dude suggested, your deck will become no more than a sub-optimal UWr Landstill build, because you'll either be forced to add more mana sources to support Decree and the long game, as opposed to if you made a UW weenie deck where you could keep the tempo you've built off.
Your manabase is indeed stretching it thin, if you want to stick to a slimmer manabase (in terms of # of total mana sources) you should drop a color and maintain the position of an aggro/control deck rather than add more reactive and late-game cards.
