At the highest level, you get access to the lounges at Starwood and Hyatt Hotels.

Personally, I tend to think the quality of the breakfast and evening snacks is much better at the Hyatt properties with lounges. The SPG lounges are typically at the Sheraton properties, but a few Westins have them as well. In general, most of the Sheratons I've stayed at have very basic breakfasts and pretty weak evening snacks. I like the free sofa drinks and water, so it's not all bad.

You get free internet at that level too at both hotels