by the way

I neglected to mention that singapore is a little funny with discount airlines.

while it's cheap to fly to bangkok from singapore and to some other locations, sometimes a taxi to Johor Bahru, malaysia, and a flight from there can drop costs substantially.

Mostly the difference appears to be in flights to malaysia, but it's not a long cab ride to johor bahru.

finally note you are mentioning a lot of destinations, bali, phuket and several other destinations.

I did six days or 7 days in bali and didnt have time to see it all.

Singapore takes like 2 to 3 days minimum, especially if you arrive jet lagged.

If you go to phuket/krabi/koh phi phi you need to spend a day snorkeling (it's gorgeous), bangkok takes several days and you haven't even mentioned borneo where the orangutangs are.

you didnt mention how much time you had for the trip, but it sounds like your trying to squeeze an awful lot into it