400 Amp service to 2-200-Amp Sub-panels
I have installed meter bases with limited service panels in the past, my last home I did what you want but you have to find the correct panel that can handle multiple 200 amp breakers. As far as the backup generator is it going to run the entire system or just one of the 200 amp subs? By setting up for one sub the cost will be much less as the transfer switches get really spendy for a 400 amp model.