Convert the whole thing before you go? Not sure if that extra step will be worth while, not te mention that some places charge a small fee for each conversion. In that case, it won't make sense at all.
I am in Spain right now and here's what I am doing. I take cash from my checking account only when I need it through ATM machines.
I pay as much as I can with my "mileage" credit cards. I get the equivalent of one airline mile per every dollar I spend. I will pay my card with the cash that I would have taken on the trip.
So, for example, if I'm gonna spend $4,000 in cash this month, I may as well get 4,000 miles for it. Sometimes they give you 2 miles for evey dollar or some other kinds of specials
In addition, using my credit card for most purchases (gas, groceries, Christmas presents, restaurants, clothes, movies, anything...), I will get the TRUE exchange rate for that day (it fluctuates minutely every business day).
So, my advice is to keep the 30k as "cash reserves" and withdrawl the money sparingly. Get a mileage credit card and build the miles up for FREE flights in the future if you'll be spending money anyways.
Let's put it this way, for your $30,000 of spending cash, that is equivalent to 30k-60k of airline miles. You can get a free ticket to travel within the USA with 25,000 miles and to fly to Europe from Los Angeles it takes 40,000- 60,000 miles to fly for free (depending on the credit card).
A list of cards that offer miles- http://www.creditcards.com/airline-miles.php
DO NOT DO IT, if you are not responsible in paying off your creditors or do not know how to manage your money. This will only build up your debt and you will drain your cash reserves as well. Not a nice place to be in....