Hello Stormy,
One thing you'll find is that prices here are considerably lower than in the West. Nevertheless, it's easy for your hard earned cash to disappear. To give you some guidelines:
1/ In HH, a meal for two in a "good" restaurant, including a few beers each, will probably set you back about 1,000 Baht. You would generally be eating western food for this price.
Eating in a "good/medium" Thai restaurant will cost around half that for the same.
If you like snacking, then you can get a good bowl of noodles on the street for 10-20 Baht. It's all good food, btw. Very few people suffer from stomach upsets over here.
2/ BOOZE. Assuming you like a few jars, I'll bet this is where most of your money will be spent.
All the bars in town are roughly the same price, ranging from 50 Baht for a small bottle of Chang (6.4%!!) to 70-80 Baht for a small bottle of Heineken or Carlsberg.
Note that a large bottle of Chang will cost 35-37 baht from a 7-11.
3/ Accomodation. you didn't mention this, but there is a huge variety of places to stay. Plush hotels can set you back 6,000 Baht a night. Flea pits, about 200 Baht. Mid range, comfortable accomodation can be found for 800-1,000 a night.
A number of years ago, I went on the wagon for a month. Just out of curiosity, I made a note of how much I was spending a day. It turned out to be on avarage 150 Baht. Accom obviously not included.
So, you can do it really cheaply, but I assure you, it's not much fun
PS. If you're coming with your partner, I assume you'll not be partaking in the delights of the ladies of the night. This will also save you a small fortune.
Hope that's of some hlep.