Is it okay for Christians to dance?

Yes, Christians can dance. Dancing is biblical.

1 Sam. 18:6, "And it happened as they were coming, when David returned from killing the Philistine, that the women came out of all the cities of Israel, singing and dancing, to meet King Saul, with tambourines, with joy and with musical instruments."
2 Sam. 6:14, "And David was dancing before the Lord with all his might, and David was wearing a linen ephod."
Psalm 149:3, "Let them praise His name with dancing. Let them sing praises to Him with timbrel and lyre."

Now, such a blanket approval of dancing doesn't mean that all styles of dancing are acceptable. In modern culture different dance styles, particularly in nightclubs, are indecent. Some movements are explicitly sexual in nature and demonstrate a lack of morality that is exacerbated by rhythmic, sensual movement. This has no place for the Christian who is to exemplify modesty and propriety.

It is not possible to give a blanket approval or disapproval and cover all possible combinations of styles of dancing. So, we need to use Christian love and biblical discernment. Let's use common sense. We are free to dance with our spouses at weddings. I am free to spontaneously dance with my wife in a warm embrace in the kitchen when we have a chance encounter. But, we Christians are not free to participate in any form of dancing that would cause others to lust, incite sexual arousal, or be touched inappropriately.