You can plan your Cochin, Kottayam and Allepey visits one after the other. Munnar is easily accessible from Cochin(120kms) and a must visit.
Wyanad on the other hand, is about 7 hours away.
You could do something like:
Cochin : Fort Kochi,Synagogue, Beach, Food at Dal Roti, Kaashi Art Cafe etc
Cochin-Munnar: Spend 2 days and one night in Munnar. Visit Maattupetty dam, Top station, tea estates, Rajamalai etc
Munnar-Cochin- Kottayam or Munnar-Kottayam, then Kottayam-Kumarakom( just 12 kms): stay, houseboat ride, toddy shop and spicy food etc
Kumarakom-Allepey boat ride, Roam around in Allepey, see the beach etc
Travel via A.C road to Tiruvalla and take a train to Varkala and then maybe Trivandrum!