I think this is a place where we have to be careful. As people who desire to see the glory of God, and see Him vindicated, I think we do look for His enemies to be made His footstool. But, it's not so much because of hatred for them, but to see God glorified in their destruction.
But, on the other side, we should be praying for them, that perhaps God would grant them repentance, as He did with us. We were also once enemies of God.
When the cyclone hit in Myanmar, I had mixed feelings. I still do. Part of me is really concerned for the safety and welfare of those who were displaced and also lost loved ones. But, another part is glad to see that God is still "revealing his wrath against all unrighteousness." Myanmar, or Burma as we usually call it, is VERY hostile in their treatment of Christians in that nation. Many of our brothers and sisters are either locked up, being tortured (or both) or have been killed for their faith in Christ.
The same type of feelings hit me with the earthquake in China. Concerned and compassionate toward those left behind, and prayerful concerning them, but I also realize how the Chinese government treats Christians.
I've been reading and getting involved with Voice of the Martyrs for about the last two years. Each month they send out a newsletter, detailing the things that are happening to our brothers and sisters worldwide and offering ways we can help them. There have been many times that I have been brought to my knees, weeping, sobbing and asking God to give me the same courage and strong faith.
So, for my brothers and sisters in Burma and China, I'm thankful for God's judgment. They've been suffering for a long time. Perhaps this is God's way of showing them that He still cares for them deeply and will not let injustice go on forever. He will eventually rescue each one of us from the wickedness of the world. That's great encouragement.
I don't pray specifically against any particular enemy of God. However, I do pray that Christ be glorified and that all those who reject Him would receive their just penalty. When Christ returns and brings judgment upon the world, the saints will be rejoicing.
But, again, I think we have to be careful with our feelings.