It really depends on how much you want to spend, whether you can eat local food or need Indian food, if you would be consuming alcohol, if you are ok to travel by public transport / in a group etc. But assuming u do a budget trip, it will cost you around 4-5k a day plus flights.
If you stay in a 4 star hotel/ villa with internal transfer using private cab/ flights. For two people it will cost 1 lakh.. It's the maximum with all luxuries. It will cost less if you stay @3 star hotel and travel through public transport. But it's better to take a package and roam freely.
I have not been to Pattaya but had been to phuket, Bangkok and krabi for 6 days. If you spend lavishly like staying in 4 to 5 star hotels, drinking and enjoying island trips then also for 2 people it will be done in 1.10 lakhs. For budget trip buy beers from supermarkets, stay near to main pub areas to avoid transportation cost. You will get 2 wheeler on rent as well in phuket and krabi. Use public transport, it is good in Bangkok. You should be done in 70-80 K for two person.
Let me know if you need any other info.. Upvote if this was useful.
I had 6N 7D trip to Bangkok, Phuket, Krabi & island hopping to Phi-Phi island (from Krabi) & James Bond island(from Phuket). Staying in 3/4 star hotel, the total budget including shopping & airfare was less than 50k.