Praying for the Promise

If God's promises are like done deals, why do we pray about them? If I have been promised that this person will come to Christ, for example, why constantly pray and ask God for this person's salvation? I've been bothered by this for a while and have come up with a couple of reasons:
1) Preparation - perhaps God will use me when He fulfills a promise, and I need to be prepared. In the salvation example, perhaps praying for the person keeps me in tune with God's plans for them and helps me be ready to act when God's ready to move.
2) Sensitivity - perhaps as I pray for a specific person, God fills me with His presence in a way that will speak to them as it pours out. He fills me with His heart for a particular person, allowing me to demonstrate the aspect of God's character that will speak to their specific needs most effectively.
I'm sure there's some truth to the above reasons, but God showed me something more. Again, both focus on prayer as a passive means to an active end. Doing instead of being again. As silly as this sounds (to me anyway), I wonder if the answer lies in the Christmas present analogy from "He Did It." My parents loved watching their children anticipate Christmas. They loved to tease us about what we thought we'd be getting ("that package is a box of dead flies" was a favorite of my father's). They knew our excitement for the big day made us enjoy the experience for the whole month of December, and made the present more special when we finally got it. And as we waited and anticipated, they shared in our happiness. God is the ultimate parent. I can't help but think that He enjoys hearing us talk about what He's going to give us with eager anticipation.
If my theory is true, how it must hurt Him if we don't believe He really wants to give something to us, or we start to think that He wasn't going to give it to us after all, or that we need to whine and beg for it in order to convince Him to give it to us. We ruin the fun. Christmas morning will still come, but we missed out on one of the best parts of the promise.
Have you ever met one of those people you love to give stuff to because they're so genuinely excited about it? I want to be that way with God.