The Mandarin Oriental has splendid views (due to the fact that it occupies the top 12 floors of a Financial District tower). Some of the bathrooms have deep soaking bathtubs with Golden Gate bridge views - very romantic
One hotel not yet mentioned is the Ritz-Carlton, two blocks in the opposite direction (up the hill, on the same street, California Street, as the Omni). No views, however, the rooms and service there (especially in the Club) are amongst the city's best.
The Palace is very historical - built as the grandest hotel in the world in 1875, the present structure dates from 1909 (reconstructed after the 1906 firequake).
For your seafood meal, consider Aqua - one of Californa's best seafood restaurants and just 2-3 blocks down California Street from the Omni:
http://www.aqua-sf.com