You can get to Copan and the Mayab ruins in a day from Roatan. You will need to leave early and catch the first ferry to the mainland Honduras.The place the ferry lands is called La Ceiba. From here you will go via San Pedro Sula and there change for Copan 3 - 5 hours of bus, Hedman Alas run one of the better quality services though if they are not handy the other buses are an experience one should take from time to time.
The bus ride is a pretty one as with most from within Central America and the smells will revive even the most down trodden weary traveller.
It should be noted and said Copan is also a lovely village, well worth the effort. But don't stop there>> Guatemala, el Salvador, Mexico....