I always change mine. Sometimes I use goat cheese, sometimes not. I slice the potatoes on the mandolin very thin and make sure there's plenty of liquid for the sauce to cook them through. Also, carmelize the onion/shallot first, then assemble.
For the sauce I make a somewhat thin bechamel sauce with salt, pepper, nutmeg and whatever cheese I feel like adding. Be careful with goat cheese it will break on you.
Coat the dish with butter to prevent sticking. You can top with a thin coat of breadcrumbs and little wads of butter. Cook it covered for the first...say 30-40 minutes, then uncover to reduce and crisp up the top.