I don't plan money for trips and almost never bother changing money ahead of time (it helps that I have a small stock of cash for most of the countries I visit semi-regularly).

Generally I get money out of an ATM in that country for my cash needs, I just try to do it in large enough batches to minimise the fees (or if I go out to dinner with a large group who are payingin cash using them as a cash machine) and spending as much as I can directly onto a credit card. Unfortunately some cards are upping their fees for foreign transactions now, something to check beforehand.