how best to have rates for express shipping?

[trillian]

We are shipping from Mexico and offer a standard rate and an express shipping option for the USA.

 

We simply have a basic start rate and a per-item charge to calculate the express shipping cost.

 

I can do this as a zone rate but I have already created a basic rate for the USA zone in the zone

rate shipping module.

 

So what is the best way of allowing the customer an express shipping option?

 

Can I just use another zone but rename it to display 'express service' or would this

not work since there is already a USA zone?

 

Many Thanks,

-Trillian