Well after reaching Ernakulam, you can visit temples and other small things there, in Munnar you'll find tea gardens and other scenic beauty destinations, in Alleppey you'll find house boat and finally you can end your trip in Kovalam where you'll find lots of beaches and other cool stuff to do....Hope this will help you as this was the schedule I followed when I visited Kerala.
Kerala is known as God's own country so it has all of its kinds of beauty. For beaches u can visit Kovalam, Varkala
For enjoying the nature fully visit Wayanad, Thekkady
For seeing tea plantations visit Munnar
Experiencing backwaters visit Allepey, Kumarakom
Want to see the busy city life Cochin has it all
Temples and other worshipping places can be found anywhere mainly in Thrissur.
here they are Alleppey – The Backwater Hot Spot
Munnar – Perfect For A Romantic Honeymoon
Kumarakom – One Of The Most Tranquil Places
Wayanad – The Land Of Heavenly Trails
Thekkady – For The Love Of Wildlife