The trip plan was:
Cochin- 1 night
periyar- 2 nights(wild life reserve)
Allepey- 2 nights (Back Waters) (i think 1 night is more than enough. but staying at a house boat is absolutely must)
Varkala beach- 1 night(can be avoided)
kovalam- 2 nights.
Shob gulo jayga tei it is best if you stay at the KTDC(Kerala Tourism) hotels. They have the best locations.
Cochin- nothing much to do, but since the flight reaches there at about 12-1 in the afternoon, there is no point going anywhere else that day. you can take the boat ride on Vembanad Lake like we did. it will take you to old cochi, jew town etc. we liked the trip all together. just lazing around.
The Ktdc resort is The Bolgatty Palace. it is a heritage resort. little expensive but amazing.
Periyar- the day you reach here, just roam around in the town. you can do spice shopping if you want. we went to see this marshall arts show(Kalahri) . it was really nice. you can also go for Kathakalli shows.
The next day take the early morning boat ride in the wildlife sanctuary. its upto your luck how much wildlife u will actually get to see.
There are 3 KTDC hotels: Periyar House(budget hotel), Aranya Nivas(Moderate), Lake Palace(luxury resort situated in an island within the lake.)
In Periyar please make sure u stay in one of these three hotels. the others just have nothing in the name of location.
Allepey: Make sure you reach here before 12 pm. and check in directly in a house boat. Please do not stay at a hotel. its a total waste of time and money. these boats start to sail at 12 pm . They serve amazing local food for lunch. u will love it if u are experimental with food. please make sure to have karimeen(a type of fish) its somewhat like pomfret but sweeter. its yummy.
stay over night. there is nothing to do after sun down except have your own party in the deck of the boat.
Varkala- its a new beach. very picturesque. but the beach is full of jelly fish. u cant stand at one place for long. not very pleasent experience. i was constantly scared of getting bitten by jelly fish.
I dont think there is a KTDC hotel here, we stayed at Hotel Hinustan Beach Resort. very well located, absolutely on the beach.
Kovalam- Amazing. this place is just amazing. please spend atleast 2 days here. on the first day we took a day trip to kanya kumari. its about 4 hrs drive. came back by evening. in kanyakumari, the last boat which take u to Vivekanada rock starts at 4. so if u want to visit the place, make sure u reach early.
In kovalam just laze around in the beach. bathe in the sea. go to the light house. take keralite spa if u want. basically just relax.
stay at the Samudra resort(KTDC). There is also a Uday Samudra resort which is a 5 star hotel, dont get confused between the 2.
In all these place it is best if you do the booking well in advance. the people are very warm and hospitable. try to keep kovalam at the end of the trip, as it is the most relaxing, and is just 12 kms away from trivandrum airport.
Food is very different. I personally loved there local food as i am very fond of coconut. at all the places, try to stick to the local small resturants for your meals. they are cheap and authentic. At a good hotel, try their Appam with Chicken stew. its very tasty. Also the porotta with korma(veg or cicken) is good.
In Kovalam have lots and lots of Prawns, squid and fish. they are absolutely fresh and delicious. they add this fresh pepper to most of their food, which turns out amazing.
you can also go to Munnar. though i personally am more fond of hill stations with snow view, so was anyways not too keen on Munnar. but its nice.
Kumarakom is also a very expensive and upcoming place. but its almost same as alleppey.
i think i gave too much details. just because i enjoyed the trip very much. loved the place. i can also send you some snaps if you want.
if you are planning to visit in Dec/Jan, i think now is the right time to start bookings and all. otherwise you will not get reservations.