Thailand in 5 days is a bit short one as we did but if you are quick , adventurous and planning to visit Thailand for just 5 days then you can try out the following :-
Th first sighting when one lands in Thailand is of Suvarnabhumi airport....
Ruins of Ayutthaya Remnants of the flood that inundated Ayutthay
Luang Pho Tho
The Buddha under the bodhi tree
Cruising along the Chao Phraya Wat Pho Wat Arun (temple of dawn) Baiyoke Tower II
at Siam Ocean World Kho Chicken Rice
Sukishi Buffet Ayutthaya
How to get there - By train, take one from Bangkok's Hualampong station to Ayutthaya....