I've stayed at the Marquis a few times on trips to San Diego. It's tough because their price is often too far above other hotels in the area to justify with my employer. Or my wife.
But IMO some price premium is deserved. The front desk staff have impressed me every time I've visited. The rooms are sizable, and as a Plat they've always given me an upgrade to a high room with a balcony. Last time I was there I scored an upgrade to an amazing suite. I would always pick this property over the Marriott Gaslamp (which I've also stayed at a few times) unless the latter were substantially cheaper.