I like
Steely Resolve 
better in your deck, since it doesn't run any spells that target your own creatures. Then again, you might as well splash white for
Crystalline Sliver 
. You're already running Gemhide Sliver and Aether Vial anyway. White also gives you more Muscle Slivers in the form of
Sinew Sliver 
.
Wild Pair is kind of odd. I believe that since you have some amount of global +1/+1 and +2/+2 in the deck, playing say a second Muscle Sliver or a Might Sliver with a Musle Sliver in play, that you can't find what you need or even nothing because it comes into play as a 3/3, 4/4 or 5/5 and you're not running anything worthwhile in those categories.
If you're looking for raw card advantage, try
Pack Hunt 
? (this
targets your creatures though. Not cool with Steely Resolve.) Getting three extra Muscle Slivers sounds like fun. Of course, since you're playing blue/green you have good card drawing options, e.g.
Harmonize 
/
Concentrate 
either of which are probably better than
Distant Melody 
because if things go bad and you
need cards now then melody can fail your for lack of creatures in play.
For melody to be better than Harmonize/Concentrate you need 4 or more creatures on the battlefield. At which point you should ask yourself "Why am I not playing
Overrun 
instead?"
Distant Melody is "win more" in this deck. The board states in which this gives you a lot of value are the board states in which you're already winning -> You have 4 or more slivers in play.
Actually,
Overrun is also considered a win-more card by some, since it's only really good if you've got a bunch of creatures in play. But at least casting it means you're probably going to win in that very turn instead of drawing a bunch of cards for next turn.
In a sense
Might Sliver 
is your personal Overrun in that it gives a huge global +2/+2 boost, which is not quite +3/+3and trample, but Might Sliver, unlike Overrun, is useful even if you don't have any creatures in play. So you don't really need Overrun.
In short:
Concentrate > Distant Melody (former being more reliable)
Might Sliver > Overrun > Distant Melody (again, former is more reliable than either)
-> cut Distant Melody
Ovinize 
is ... pardon the pun.... meh. Unless
Blightsteel Colossus 
is a major force in your meta. Even then, something like
Temporal Spring 
is probably nicer. No card disadvantage, you can possibly counter it, if your opponent attempts to recast it. Which Reminds me, with 11 blue sources Counterspell is not optimal. I think
Mana Leak 
is better here. If you're splashing white, nobody will keep you from playing
Swords to Plowshares 
or the budgety
Oust 
/
Condemn 
etc.
Lands:
Try getting your hands on
Hinterland Harbor 
//
Yavimaya Coast 
//
Misty Rainforest 
instead of the guildgates. They negate quick Aether Vial starts. You either have to skip your turn1 Vial or skip your turn2 Sliver of Choice.
Most rare duals are incredibly pricey so your best bet is
Yavimaya Coast , which is only about $2. It may seem unexciting but painlands are really so much better than the guildgates. Often you'll not even have to pay any life, because you have the right mana anyway. And on your first 3-4 turns, they don't hamper you development like the guildgates do. Also it just sucks to wait for your fourth or fifth land and have it be a tapped land. UGH!
