To give you some precise data, I would need you to clarify exactly where 'into the city means'. In any event, driving from the Sheraton Bandara into town should take between 20-30 minutes with no traffic. However, during morning rush hour, it really depends where you are going.... but to give you an idea, if you are going to the Jl. Sudirman area or similar sections of town that are inside the 3 in 1 area (as in three people in one car), it could take very long. By using a taxi you will be exempt of this rule, but still the whole city traffic goes nuts when 3 in 1 is in effect. If you can drive after 10am and before 4pm you will be better off.

To sum things up.... allow at least 50 minutes from the Sheraton Bandara into town.

Cheers!!