It's hard to tell Thomas, The worst of the flooding (a meeting of floodwaters and some king tides) is expected from 27th to 31st October. So the worst could be over when you arrive, or it could still be a disaster.
NOt sure where you're from, but the British, Australian, and NZ governments are warning their citizens to put off all but essential travel to Bangkok (and the other flooded provinces). They're warning that not only will the streets POSSIBLY be teeming with filthy water (think about all those sewerage systems flooded), but the crippling effect on infrastructure and transport means it may be difficult to get fresh water (even in bottles), food or essential medical supplies.
The international airport remains open (and is unlikely to be affected), so if I were you I'd be booking onward tickets to anywhere else in Thailand - Chang Mai and anywhere south of Bangkok is unaffected - so you'll still be able to go to Thailand but avoid the mess that could strike Bangkok.
One other important note..... as far as insurance is concerned, if you already have a policy (and bought it before all this flooding became big news) you might be able to make claims for cancellation and delay (of course there are conditions). If you still haven't bought travel insurance, it's not too late to get a policy that covers you for medical costs and theft etc, but the cancellation and delay clauses will be excluded (you can't insure your car AFTER you've crashed it). almost 7 years ago