I like the super thinly sliced sourdough bread that La Brea Bakery uses on their grilled ham and cheese. Ciabatta sounds pretty fantastic too. You have to be careful not to get a roll that is too thick or else it won't heat through all of the ingredients.
Remember - the trick for beautiful grill marks is to spray/brush oil on the outside of the bread and not the grill ;)
-Trader Joe's has panini rolls in the bread section in a white paper bag, 4 to a bag.They are pretty good.
-Whole Foods has them in the bakery case section where the muffins, cookies, etc. are & they are sold individually. Also pretty good.
-Bristol Farms also has them in the bakery section, 4 to a bag.
Can you tell someone here got a panini maker for Father's day ?
I have been on the hunt too !