I would suggest Allepy, here the main attraction is the famous backwaters of Kerala. What you could do is, rent a house boat for a day. It would cost around 10k approximately. They will take you through the backwaters and you will get to eat some delicious sea food. The house boats will be moving till 5pm if I am not wrong. You can stay the night in the boat, it will have comfortable AC rooms with all amenities. You can also try the famous "kallu" which is the alcohol from the coconuts. Another destination would be Wayanad, if you are into hill stations. It'll be cold and beautiful too. Find yourself a good resort where you could do fun activities. I would suggest Vythiri Resorts.