I just booked a trip to cozumel for our family of four including twin five year old boys. We will be in cozumel for 7 nights but we are also interested in taking the ferry to the mainland to see some ruins. Question: Can you see some great ruins in a day trip or would I be better to spend the night there? We are flying in and out of Cozumel so we must return back to cozumel but would love some of your input of seeing the ruins, which ones to see, and how much time is needed to do it! Thanks so much!