I went from 275/65R18 (32") to 275/60R20 (33") with no rubbing on stock coil suspension. I lost 1-1.5 mpg with the 1" diameter increase, but I also am driving the V6 so I cannot testify for those driving the V8. When selecting your tire, pay attention to the load rating and weight of the tire. You will lose more mpg with LT tires because in some cases they are 10lbs heavier per tire than XL or P rated tires.
With my tire swap, I lost 0.5" of sidewall and my drive is now less cushiony, but I also believe the driving experience on the stock 275/65R18's was too soft to begin with. That being said, if you are going from 275/55R20 to 275/60R20, you will be gaining an extra 0.5" of sidewall and your ride should be softer, although you may not be able to notice a significant difference. You can get a visual representation when comparing tire sizes using this tool:
https://tiresize.com/comparison/
Road noise will depend on what tire you get. A few models that I have read good user experiences for low road noise are Nitto Ridge Grappler, Hankook Dynapro AT2, Toyo Open Country AT2, Cooper Discoverer AT3 4S, BFGoodrich KO2 and Falken Wildpeak A/T3W.