Vaikuntha Ekadashi at Padmanabha swamy temple, Thiruvananthapuram, Kerala and at Badrachalam Sri Rama temple, Andhra

The annual  Vaikuntha Ekadashi fesival, that is celebrated on a grand style during mid december and mid January  at famous Vishnu temples is a popular one in South India, in particular, Tamil Nadu and Andhra states. It is not a big religious function in Kerala in comparison to Tamil Nadu where the historical temples steadfastly follow centuries-old rituals, etc. These rituals still remain unbroken and are bring followed with more vigor than ever before.  Though the Indian states, language-wise, stand apart, culturally and religiously, as far as Hindu festivals are concerned, they are quite similar and Hindu temples in the respective states, follow more or less   same rituals sans format and style of presentation of some festivities.  
Sree Padmanabhaswamy Temple, Thiruvananthapuram, Kerala:

Padmanabha Swamy Temple,Thiruvananthapurm, Kerala,Alamy com

Sri Anantha Padmanabha Swamy Temple in the prime  locality, close to  the Thiruvananthapurm Central railway station, Kerala is one of  the most famous  Vishnu temples in  south India and is the world’s richest temple.  The temple has vast treasures in the form of gold coins, gold jewelry, diamonds, valuable gemstones, gold idols, etc., worth  more than US $ 25 billion stored in the under ground vaults.  Mind you, the antique value of the old treasures on the present international market is not taken into account and it many add up atleast 4 times more than the present estimate.

Padmanaba swami templeVishnu, view thru' thee doors

The main deity of this temple has Ananthasayanam posture,  the reclining posture on the coiled bed of the serpent Adisesha. The Moolavar is  visible through  three main doors before the savtum. The head of the deity and the serpent Adisesha is viewed through the first door, the naval of the deity and the gold idols used for daily anointing and poojas is seen through the second door and the patham (Feet) of the deity is noticeable through the last door. The important fact is, in the case of worship at Vaishnavite temples, Patha dharsanam - worship of the divine feet of the lord,  is fore maost important and it is symolic of surrender to the Almighty (sranagathi). The deity, being a big one, is made up of 12,008 Saligramams  (a sort of fossilized stones found in the sedimentary rocks of the Paleozoic period in the  Himalayan mountains)  collected from the Gandaki River of Nepal. Hindus have a strong belief that the whorls (chakra image) in the stone symbolize Sri Vishnu and you will find the Saligrama stones in all Hindu households. Devout Hindus, both Vaishnavites and Shavites do pujas to them frequently.   

In Kerala Vaikunta Ekadashi festival is called Swargavathil, meaning Passage to Heaven and is observed in the Malayalam month of Dhanu. As in Tamil Nadu,  the processional deities  from the sanctum -Srikovil are taken reverentially in a procession  through the Vaikuntha Dwara ( similar to Paranapada vassal). It a colorful and vibrant event here  and people in thousands walk through the Vaikuntha Dwara in the belief, Namperuman will
bestow them good health, welfare and most importantly peaceful life.  This festival is not an elaborate one as in Tamil Nadu where the temple priests are vaishnavite Brahmins - Bhattachariars. Here, at this temple, the priests are Namboothiri Brahmins and the chief one are called Nambies.

Sita Ramachandra Swamy temple, Bhadrachalam, Andhra Pradesh:

Sita Ramachandraswamy temple, Bhadrachalam,

At Sita Ramachandra Swamy temple, Bhadrachalam, Andhra Pradesh, the presiding deity is Sri Rama, seventh avatar  of Lord Vishnu. Located on the banks of the Godavari River,  this historical temple (associated with Bhakta Ramadas, a great devotee of Sri Rama) is one of the Divya Kshetrams and is also known  as Dakshina Ayodhya. Vishnu appeared to Meru’s child Bhadra as Sri Rama  and  overlooked that Rama was a mortal human and showed up as Vaikuntha Sri Rama with four hands.  There are idols of Rama's consort Sita and brother Sri  Lakshmana as moolavars in the sanctum.

Sri Ramachandra swamy temple, Badrachalam, AP.

Vaikunta Ekadashi festival is the most  popular one here.
The temple with presiding deities as Lord Rama, his consort Goddess Sita and brother Lakshmana  is a popular center of pilgrimage in Andhra Pradesh. On the day of Vaikunta Ekadashi festival, the utchava deities of Lord Rama, consort Sita  and brother  Lakshmana are taken out in a religious  procession through the Vaikunta Dwara,
quite similar to the temple tradition  being followed in Tamil Nadu and elsewhere. Quite interesting is the fact that the Vaikuntha Ekadashi celebrations held here  are based on the traditions of  Srirangam Ranganathar temple, TN.  

As per the Bhadradri Kshetra Mahatyam (Importance of Bhadradri) in the Brahma Purana, devotees who visit the temple here  and seek  the blessings of Vaikuntha Rama on the annual festival day of Vaikuntha Ekadashi,  shall be granted  Vaikuntha propthi - salvation in the shadow of Sri Vishnu's abode. The Agama text Paramapurusha Samhita  has mentioned that the devotees should pray to Sri. Vishnu seated on the Garuda Vahana  while taken with reverence and devotion in the procession through the Vaikunta Dwara  - North gate to fulfill their wish of gaining salvation. On the day of Vaikuntha Ekadashi in the early morning, the utsava idols of Rama, Sita, and Lakshmana on the Garuda vahanam will be carried  by the Vaishnavites through the Vaikuntha Dwaram- Sorgha vassal. Later devotees are allowed to  pass through the Vaikuntha Dwaram.

Yet another event as part of  prelude to Vaikuntha Ekadashi, is Teppotsavam (the float festival) that is celebrated  with pomp and religious fervor. A boat  shaped like swan named Hamsa vahanam is used  for the procession of the utsava murthies (idols) on  the waters of the near-by Godavari River.  During the Teppotsavam  the entire place is well-lit, using flood lights for the benefit of devotees  to enjoy this annual event and there will be fascinating, colorful fire-works at night  The  decorated boat carrying the idols makes five long circles in the water and normally about  26  devotees, including temple priests  accompany the float procession.  As at Srirangam temple, the festivities last for 21 days and Goda Kalyanam and Rathotsavam (the chariot festival) form  important activities of the annual  celebrations; the latter event coincides with the Makar Sankranti festival. This unique festival draws people in thousands from near-by districts as well.,_Bhadrachalam