as much as you can afford, especially as clothes etc are so much cheaper. Take what you can and work out a budget from that, do you have credit cards ?
You will have a great time with �500 each but there is always room to spend more, but one of you should take charge of the money, especially if you are going for 2 weeks, budget 35 $ dollars a day per person for food, then there are refreshments during the day, its hot and you will gt thirsty, so say $50 dollars a day to cover all, then there are your theme park entrances, try and by your tickets before you go and thats another expense out of the way, your girlfriend wont be allowed to drink in any bar because she is under age but you can buy from a liquor store if you show ID. I could go on, planning ahead is the best idea. If you intend to go mad buying clothes then dont travel with too many and buy as you go along, put one smaller case inside your big case to get the stuff back.
have fun.