Just to take a little bit different take on the question, the reconciliation BETTER be genuine because Shakespeare's Romeo and Juliet is a tragedy, and as such does end with death, . . . but should also end with an inkling of hope. (This, of course, is the opposite of a comedy which would end in a "happy" marriage, . . . but should also end with something at least a tad disturbing.) To suggest something different is to destroy my entire thought process regarding comedies and tragedies. SO, although I'll admit that most of the words of professed reconciliation come from the Prince and not the heads of the feuding families themselves (which in itself is a bit disturbing), the heads of the Montague and Capulet families do participate in a few of their final statements of the play. For example, Lord Montague and Lord Capulet do shake hands as evidenced by Lord Capulet saying, "O brother Montague, give me thy hand" (5.3.309). I believe a handshake in itself does constitute a significant bond. In addition, I think honoring the child of the opposing family is a grand statement of reconciliation:
Lord Montague: But I can give thee more; / For I will raise her a statue in pure gold, / That whiles Verona by that name is know, / There shall no figure at such rate be set / As that of true and faithful Juliet.
Lord Capulet: As rich shall Romeo's by his lady's lie--/Poor sacrifices of our enmity. (5.3.312-318)
Done, and done. But what's truly exciting is that this is one of those glorious examples when the text can be used to support either theory. It's so wonderful when that happens, . . . as it shocks the heck out of my advanced students!