I see several tangible differences between Gold and Plat:

1) Modestly better bonus of 30% on top of base vs 25%

2) The 48 hour availability guarantee - I have only used this twice but boy is it nice when you need it. In one case to get into the CbM Morgan Hill CA during the Gilroy Garlic Festival, and once to take my kid to the Jersey Shore in peak August demand w/o a res and everything sold out.

3) The Plat arrival gift, I always take the 500 points. If they forget and you choose to call them on it, you get $100/$50/$25 at FS/mid/FI.

4) Better upgrades, even on corp rates and award stays. I have had some amazing upgrades this year, including 24th floor oceanfront at Marriott Waikiki on a cheap corp rate, the Presidential Suite at Marriott ONT, ocean views on high floors at Marriott SAN Resort and Marina on a city view rate.

Of these bennies #2 and #4 are the most important to me.