I'm assuming you're from BOS based on your post, and that you wanted to use all 4 certificates on the Hawaii trip.
I suggest doing two end-on-end tickets. The closest place on the mainland from which CO serves HNL is LAX, so if you buy two tickets each, you can get to Hawaii for about $50 + taxes (after certificates):
1. Buy PVD-LAX-PVD on a currently published $198 or $258 fare, less $250 vouchers.
2. Buy LAX-HNL-LAX on a currently published $349 fare less $300 vouchers.
I selected PVD because BOS was too expensive.
Doing it this way also allows you to stop in LAX in either or both directions if you want to.
[This message has been edited by channa (edited 01-06-2003).]