If you have your heart set on Copan I would not go to Lanquin. It is just too far. Rio Dulce makes the most sense. You have only 5 days left. A day to get to Rio Dulce. And then you have three days for the boat trip to Livingston and a few nights in a hostel on the river like Hotelito Perdido or Finca Tatin for kayaking and hiking. I don't see how you would add Tikal as well.
If you pick Tikal instead of Copan you can choose Lanquin or Rio Dulce. Although the boat ride to Livingston is scenic I didn't find Rio Dulce or Livingston all that attractive. El Hotelito Perdido was nice but two days was more than enough.
Lanquin is a rural Q'eqchi' Maya village. It is set in a lush valley. There are coffee and cardamom farms on the lower slopes of the hills that surround the town. We enjoy the scenery in and around the village, the caves, the river and of course Semuc Champey. But we also enjoy village life. The buses coming and going, the church, the small market and near Semuc the kids selling chocolate. One year I hope to visit Lanquin during the fair in August.
Maybe you could start with Tikal and somehow fit in Rio Dulce, Copan, Antigua and Lake Atitlan. Day 1 fly to Flores or overnight bus. Day 2: Tikal. Day 3-5: Rio Dulce. Day 6-7: Copan. Day 8-9: Antigua. Day 10-12: Lake Atitlan. Or skip Rio Dulce but I don't know if you can get from Flores to Copan in a day.
Or start with Tikal and Flores day 1-3 and then 4 days to get to Lanquin, enjoy Semuc Champey and get to Antigua. 5 days left for Antigua and the lake.
Or start with Tikal and Flores, then Rio Dulce and then Antigua and the lake.
