I'm an ENTP married to an INTJ for over 3 years.
We often find ourselves thinking the same thing in the same situation. We can sit in silence together for short periods of time without feeling awkward, but I usually find something to do if the silence lasts too long. I thrive off attention while my wife prefers solitude.
My wife is calm and level-headed, I tend to be restless, impulsive and grandiose at times. I can be easily frustrated and impatient when inconvenienced while my wife is slow to anger. I push forward for novelty and change, while my wife prefers stability and routine.
I can come up with wild ideas sometimes, while my wife is able to bring me back down to Earth. Conversely, I encourage my wife to try new things, take risks and expand her horizons (with mixed results). Both my wife and I are intensely loyal and defensive of those we love. We're both (mostly) laid back towards others in relationships and most minor irritations roll off our backs; we both can hold a big grudge indefinitely if we feel our trust has been severely violated. My wife is naturally organized, while I tend towards disorganization.
It's a great relationship combo. Each person's strengths compliment the other's deficiencies, but yet, there's that commonality of "being on the same wavelength" that creates wonderful intimacy and attraction. When others observe your relationship from the outside, they might not "get it." They'll wonder, "He (or She) is so quiet and reserved, and she (or he) is so outgoing and fun." In my personal experience, I've dated other extroverts, and the relationships ultimately failed. Two people competing for the spotlight generally experience a lot of conflict!