Where to Visit - w/e Indonesia

If its just for the week-end (2-3 days?), Singapore would be a good idea IMO. Its easy to get to from JKT & its easy to get around using the efficient/cheap public transport to the local attractions eg.Mandai zoo, Jurong birdpark, Little India.

some ideas for java

I suspect that to some degree where you decide to go will depend on your interests which you neglected to mention.

I will be spending a weekend in September is Jakarta and it was suggested that if I wanted to get out of town, I consider going to Bandung or Bogor. I am told that Bandung is known for its colonial architecture, cooler weather and Sudanese culture. Bogor's main attraction is botanical gardens and the former residence of the Dutch colonial governers/presidential summer palace.

There are cheap flights to Singapore and there is plenty to do and see there. If you decide to go to Singapore, there is a good tourist office in the airport which can help. Again, it is hard to know what to suggest you do and see there as you haven't indicated your interests.

Ruth

The north coast of Lombok would be a nice place for a quick visit. There are quaint little Muslim villages along the coast and you will be the rare tourist if you get off of the beaten path (i.e. away from Sengiggi)