Underestimating and disregarding the junior people or those without impressive titles is the hallmark of phonies, and you can spot them from a mile away. This is not to say that, as a rule, touching base with as many people as possible should be avoided. There is a right time, place, and manner in which to do so. But in many situations, it is far more rewarding and enriching to meet a few interesting people, learn what they do, how they do it, and discover if there is a convergence of interests. True and successful networkers treat everybody with sincerity, courtesy, and dignity, knowing that good manners buy good will.
People are like the stock market.
You never know who will be up and who will be down the next day. Taking the long view, giving everyone her or his due, is the best way to build a real network and to ensure that things will fall in place for you.