ATM's are readily available all over Bali. Basically all of the major commercial banks in Indonesia are linked in to the international ATM networks (Star, Plus, Cirrus, etc.), so ATM cards from US banks should work reliably in almost any ATM you find. And almost all have English functionality options.

The only proviso to that is that some ATMs limit the amount of withdrawal you can take (not sure why, maybe running low on cash) at a single whack. So even if the screen gives you a Rp 2 million option, you might get an error message on the next screen because the machine doesn't really want to give you more than Rp 500,000. If you run into this problem, just find another machine and try again.

Personally, I don't like it when an ATM gives me Rp 2 million in 50,000-rupiah notes. Forty of those notes is very thick and gets inconvenient when folded over in my wallet. But unless the machine has a little sign indicating that it'll give out 50,000-rupiah notes, you won't know what denomination you're going to get until the machine spits it out.