The well-known (and beloved) song from the Hagada is introduced by the line: KAMA MAALOT TOVOT LAMAKOM ALEINU - How many good things did G-d do for us.
There are 15 items on the list, which means 14 DAYEINU couplets in the style of - If G-d had (just) done this, but not done that (the next item on the list), DAYEINU - we would have sufficient cause to thank Him. DAYEINU certainly doesn't mean ENOUGH, as in, it would be enough - because - just to use one example - had He brought us to Har Sinai but not given us the Torah. it would NOT have been enough.
Torah was the reason for our being at Har Sinai. But our experience at Sinai (aside from the Torah which we received there) gave us sufficient cause to thank G-d.
This is what DAYEINU means. G-d took us out of Egypt and gave us the Torah in order to bring us to Eretz Yisrael to live a life of Torah (t)here, which is able to be complete and full only with the Beit HaMikdash. Nothing short of that is enough. But every step along the way is sufficient to give us cause to express our appreciation to G-d.
We need to thank G-d for the whole process of Y'TZI'AT MITZRAYIM. And we do, by observing many different mitzvot and by saying many different prayers. We need to appreciate the Shabbat on its own and as part of the package deal G-d made with His chosen nation.
We need to value Torah anywhere in the world, even while we must realize that the intended venue for Torah and Jewish Life is Eretz Yisrael. We need to value coming to Eretz Yisrael on its own, and in perspective of everything we are supposed to do and be here.
Which brings us to DAYEINU line 14: If G-d had just joined forces with Tzahal and brought about the miraculous victory in the Six Day War, and the return of Jerusalem into Jewish hands, and not (yet) built the Beit HaMikdash (and everything that goes with it), DAYEINU, there would be sufficient cause to thank Him. That's what we must do on Yom Yerushalayim, even as we realize that there is so much more we are hoping and praying for AND working towards - still to come. May we be thankful enough to Him and wise enough to say thank you to Him for what we have so far - even as we pry to Him for more - and may we merit the AL ACHAT KAMA V'KAMA in its totality - speedily in our time - amen.