Advice for Guatemala and possibly nearby?

I will be spending a few months in Quetzaltenango/Xela Guatemala but I will have weekends free and have reserved some time at the end of my trip to be a tourist.

I'm thinking about Antigua, the Copan ruins in Honduras near the border, possibly a trip to San Sebastian in Mexico. My strenuous hiking days are behind me but I like views, nature, animals, birds, architecture, history, good food and nice people.

I am very open to suggestions. People who know the region or have visited, what advice can you share? I am somewhat budget conscious.

Edit, my concerns about Yellow Fever were assuaged by @occlude