3g plan for an officially unlocked iphone 3gs in the usa

[twit1977]

hi everybody ,

i am planning to visit the usa for about 2 weeks next march and the cities i will be visiting are newyork , la , san fransisco and vegas .

what i have is an officially unlocked iphone 3gs that was bought from hong kong .

what i need is a 3g pay as you go plan for my iphone , so can u guys help me with that ?

thanks