Anyone have experience with prepay mobile data in Waikiki and Maui (Wailea) to tell me what I can do to get the best speeds and most data for the least spend?  When I was in the USA (CA) last time, I got a T-Mobile prepaid simcard, but I couldn't use 4G Speeds because I didn't have a locked phone with that carrier, I'd like to avoid that this time if possible, or I would consider a LTE WiFI Hot Spot, but I am struggling to see if LTE is available in those locations. 

Anyone who can shed some light would be much appreciated. I have a month to get everything sorted.

My Phone is a Galaxy SIII