You may try going NW to IAH and conx with CO...they fly daily to GUA. Their fares should be quite reasonable. I believe if you do a flight search on Travelocity and the like from DTT to GUA it will give you the DTT-IAH on NW then IAH-GUA on CO. June is not a popular month to go to Guate so hopefully you will get space and a good fare!
Good Luck!
Gatowoman (a Guatemalan

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