The deal was, if the northern states agreed to put the U.S. Capitol in a southern area (as opposed to Pennsylvania which was their choice) then the southern states - which had largely paid off their debts - would agree to transfer the northern states' debts for the war from the states to the federal government.
President Washington liked the Maryland-Virginia plan because his home, Mount Vernon, is only about 15 miles from the District so he could, in effect, walk to work.
It is also useful to remember that the Constitution was Governance Two-Dot-Oh. The original government document, the Articles of Confederation, were so carefully drawn to limit the power of a central government that they soon became unworkable and what became the Constitutional Convention which convened on May 25, 1787.
Even at that, the Convention was designed to refine the Articles of Confederation but, "the stated goal of the Convention - the revision of the Articles of Confederation - was quickly discarded, and attention given to more sweeping changes."
The Constitution was ratified on June 21, 1788 when the ninth state, New Hampshire, ratified it. But it wasn't until the two largest states, Virginia (June 25, 1788) and New York (July 26, 1788), ratified it that it was clear that the Constitution would be the governing document of the young republic.
The first Congress met on March 4, 1789 which is commonly noted as the date the Constitution became the supreme law of the land. President Washington wasn't sworn in until April 30 that year and other part of the document became effective when the infrastructure was available to support them.
Nevertheless, it is a remarkable document. When it is read aloud in the U.S. House this week, you might think about TiVo-ing or DVR-ing it and having the kids sit and watch.