Just Passing Through:
Unless I am mistaken, there is no downtown Marriott in Jacksonville - IIRC, the closest and only full-service Marriott in Jax (excluding Ponte Vedre Bch) is 6 or 7 miles from city center on I-95. As far as I know, only two hotels are truly "downtown" - the 3-star Hyatt and the much smaller, 4-star Omni. That's why the Hyatt gets so many convention crowds and groups.