Advice on holiday tour from Hyderabad, India to Sri Lanka/Malaysia/Indonesia/Thail…

I'm in Hyderabad, India. I'm planning to go on a 3-4 day budget, economy holiday trip to Sri Lanka or a south east Asian country - Malaysia or Thailand or Indonesia - in the month of August or September. Could someone give me advice, tips on choosing the right places, weather conditions, local cost of living and expenses, choosing the right travel agent, air tickets, visa formalities, hotel stay, or choosing the travel package, etc? Please give me any information, from your own experience, that you have that will be helpful to me in planning my holiday. I shall be travelling with my wife and infant child. I see a lot of packages being offered on some travel web sites but most are confusing. I don't know if it works to be cheaper to go with a package or plan on my own like air tickets, hotel bookings, etc. Thanks.