PNG from Bali for a week - worth it?

Hi, I've just got flights to Jakarta and I don't have time to plan as I'm gonna be travelling until a few days before the trip. I have 2 weeks and I am thinking of spending 1 week in Bali and Gili islands and would love to spend another week in PNG. The only flight I found from Bali to PNG was sooo expensive. Is there any practical and cheaper alternative? I'm travelling with my wife and 2 kids (4 and 2 yrs) and we're mostly after beaches and chilling although in PNG we'd want to explore the island's culture too. Do you think it's worth the hassle and expense to go to PNG for a week or should I stay in Indonesia and maybe go to Raja Ampat instead? Thanks loads.

we just did our second PNG adventure flying from bali for 3 weeks - the flight leaves DPS monday night
and arrives POM early tuesday allowing you to catch an internal flight somewhere else
flight cost is similar to the flight from singapore

the return is monday afternoon so you can fly into POM monday morning but you would be much
safer to fly in on sunday an spend some time in POM - if you miss the flight to bali the next is a week away !

so on this itinerary it is possible to visit one or even two places in PNG but you would be only
skimming the surface rather than exploring deeper - rabaul is probably the best place for a short visit
as it has beaches, diving, volcanoes, trekking WW2 relics and (inland) traditional cultures

anyway if you want beaches and chilling PNG is not the place especially with small children - it is very expensive with few facilities and has health and safety issues - bali or other parts of indonesia would be much better

personally i would say miss the gili islands (very touristy without the charm or facilites of bali) and spend a week in bali and a week somewhere else in indonesia - eg rajah ampat, lombok, nusa tenggara

save PNG for when your children are a bit older so they can appreciate it and you have more time

With kids of 4 and 2 you shouldn't be thinking of PNG or Raja Ampat. These are 'adventure toursim' destinations involving discomfort as well as considerable time and expense to reach.
Rather restrict yourselves to Bali and/or Lombok. I too wouldn't recommend the Gilis with children. Gili Trawangan is best enjoyed by travellers before they have kids. Gili Air might be suitable with kids but the beach consists mostly of sharp coral.
Probably you should confine yourself to Bali or a comfortable resort in Lombok, either in Sengigi or Kuta, south Lombok. Also, it might be more comfortable to fly between Bali and Lombok than take a fastboat.