if you have cricket or metropcs in your area thier worth looking at as well , in my area Metro pcs is unlimted phone/text/data $50 a month. 2 phones $90 a month. no contract month 2 month (downside is phones are not discounted and dont have as many phone options).
As far as world travel i have a UK phone that I swap sim cards out on where ever i go. Not good for bizness maybe as number always changing but suits my needs.