I stayed in the Ammos, I would say the only potential downside is that the pool is a little small, but OTOH its relatively shallow and certainly fine for a 7 & 9 year old even if they cant swim, they'd be able to stand up in it even at teh deep end I think! (but check wth the manager, however there were a few kids in it of that sort of age whilst we were there with no issues.
The beach is just steps away (If it was any closer it would be in the room!) and pretty shallow for a fair way out, with another nice similar beach set in a small bay, less than 10 mins walk away.
We were in a room rather than a suite with kitchenette so I cant comment on them.
It was quiet, no road noise at all that I noticed, as its set back maybe 50m from the relatively busy main road. Its also in very good condition (re your comments re new or recently built). Whilst we were there (a year ago) they were building a hotel or apartments right next door but that must be finished by now.
I booked directly, mainly to make sure I got the hotel and flights I wanted, packages can let you down, they say you booked the hotel but then when you turn up......and IME they generally are no cheaper anyway.
We had a car, not sure what the price of a taxi to and from the airport tothe Ammos would be if you booked it yourself, email the manager and ask him. You could definitely get by without a car there if you wanted, I presume your kids will just want to hang about by the pool and beach all day anyway,and there was a bus into Chania, though we braved the traffic and drove in, not necessarily a good idea!
We ate at the Ammos about 50% of the time, there were several other places nearby (within 5 min walk) we also tried just for variety but in the end decided we might as well eat at the Ammos each night. ISTR they also did 'kid friendly' food like burgers and pizza etc.
If you do hire a car, take the time to drive across the mountains and down south to Paleochora. In fact, if I was to do it again I wouldnt mind spending few days there as well, looked like there were some good day trips you could take to 'hidden' beaches and dolphin watching etc that werent doable for a day tripper.