From Calicut to Thiruvananthapuram, the Maveli express is ideal choice. It is fast, clean and comfortable. You board the train at Calicut at 2200 hrs after all your work and dinner. The train reaches Trivandrum at 0700 hrs and you are fresh for work after a good night rest.
The best option for travel to Kozhikode is the Jan shatabdi express. The one I went on was the Malabar express. It has many stops and is usually a delayed train. The food served in the train is also of poor quality. The sights in the journey are pretty interesting. The long bridges and the rivers will capture your eyes.
The train that I prefer is a limited stopping train so generally I don't have to face much time in consumption of journey. Only problem is that it is very tough to get the particular train. But it is fast and reach very comfortable to my destination at noon.
The travel from Trivandrum to Calicut is across the state of Kerala, by passing through the major cities. Travellers need to make their own arrangements for food. The seats are good and AC compartments are available. The train is on time and the timing is good. The departure is at 2 pm and arrival is at 9 pm.