Hi, Kohunlich and Chacchobben are both great Mayan ruins, however to explore both on one day may be a hassle since they are situated in different directions from Mahahual, Chacchobben north and Kohunlich south. Chacchobben tours last approx. 4 hours and to Kohunlich 6 hours. Also take into consideration that if you do it with a taxi, a flat tyre on the way is not a great experience, there is nothing around...Kohunlich 2 hours driving each way and Chacchobben one hour. Hope this helps!