I agree with #9. In addition, note that many hotels in Ghana quote prices in both dollars and Cedi, and usually the dollar price works out a fair bit more. If you pay by credit card you pay the dollar price, often with a service charge on top. Moral: get to a Forex and exchange dollars for enough Cedi to pay your bill that way.

Euros are better in Togo and Benin.
Forget Mastercard. Useless in West Africa. Use a visa debit card. I ve found ATMs plentiful in major cities in Ghana and Togo and had very few occasions when my visa debit card from a UK bank was not accepted. Away from big conurbations you can struggle to find a functioning ATM.
Be warned in Benin I experienced great difficulties finding ATMs which worked and / or acccepted my card. I suggest bringing plenty of cash with you to Benin.
Also be warned credit card fraud is rife across West Africa, I would suggest paying cash only for goods or services and don t do what I did which was make an online payment from an internet cafe in Burkina Faso using a debit card. All a bent hotel employee needs is your credit card details and date of birth (from your passport) to start impersonating you and cleaning out your bank accounts...

Thanks for all the good info!
How much money in cash would you suggest I bring for 2 weeks and 2 days?
(Also, about the 'local bank' I meant a bank local to the city I'm living in now. So instead of Chase or Bank of America open a branch at First Tennessee or 5/3rd bank... something smaller. Supposedly some of them do not charge ATM fees)

How much money in cash would you suggest I bring for 2 weeks and 2 days?
Depends how lavishly you want to live. Good basic hotel / guest house accommodation is around 10 - 25 USD / night for a room with / without en suite. You can eat on the street (not recommended) for less than 1 USD. An omelette or meat and spaghetti or rice in a sit down cafeteriat or chop house will cost about 2 - 4 USD. Bottle of beer is around 1 USD.
As an example, to travel from Accra to the border with Togo will cost you no more than 10 USD by bus.
To get into most tourist places, museums or whatever, will cost you about 4 USD, less in some cases, but allow that as a rule of thumb. A half day trekking with a guide organised 'officially' ie by an outfit with a website and an office around 8 - 15 USD.
So to be comfortable, 50 USD / day, but if you can be a bit more careful, you can do West Africa on 25 - 30 USD / day but you will have to be careful with your cash.
Travel in shared taxis or buses is cheap but beware pickpockets and bear in mind some people especially self appointed 'guides' are there to part you from your money. Most 'guides' I ve encountered won t tell you any more than whats in the Lonely Planet book. Africas funny, I could give loads of advice but everyone just finds out the pitfalls themselves, the hard way. be prepared to 'lose' a certain amount of cash one way or another.
One other hint: Porto Novo in Benin has similar stilt villages to Ganvie on a lagoon. Lot less touristic, a lot less hassle and a lot less expense. Any of the fishermen will take you out in a pirogue.
The central market in Lome, Togo is a great afternoon out, people come from across West Africa to buy from the wholesalers here. Its a wonderful place to get textiles as well as arts and crafts. Save some money for shopping!

For Ghana, you can exchange some money at the airport-- just enough to get you to the hotel. Then find a bank near the hotel and exchange money there since you'll probably get a better rate than at the airport. Alternatively, use a Visa debit card to take out money from bank ATMs. If you have Bank of America account, you can get money from Barclays ATMs without BoA charging you foreign transaction fees. At least this was the case when I was in Ghana in June. When I used my debit card at other banks, BoA charged me fees. Whatever you do, don't exchange money at the hotel-- you'll get a bad rate. But you should be able to pay your hotel bills in dollars. Also, if you go to a forex, sometimes they give you one rate for $50 and $100 bills but a different rate for $20 bills. Ask a lot of questions when you exchange money and count your bills!