I haven't been to Dodgers, but they have a reputation for being a pretty terrible hotdog due to the sponsor being mediocre.

On the flip side, all of the Chicago stadiums are sponsored by the best in the business, Vienna.

When I was more directly involved in lower-scale hotdog slinging, we'd get a similar result by holding the buns in a steam table, making them warm and fluffy. Boil a pack of hotdogs, finish them on the grill... A boil-grilled Vienna 6" 6:1 on an S. Rosen (Alpha Baking) 5" bun with diced onion, celery salt, mustard, and ketchup... Perfection.

Pretty much everywhere in the Chicago region uses the exact same hotdog bun you can get in every grocery store here. Most stores don't carry the poppyseed variant though.