The more barracks the better!
I've heard asked many times how many barracks/cottages should you have?
With full fields i like 5 cottages and the rest barracks.
Buildings you don't really need:
After main training you only need 1 alchemy lab in one city and I only build 2 alchemy labs at the beginning of the game, for faster researching.
The other cities just use the extra spot for one more barrack.
Please Note: Leave one Alchemy lab for future upgrades!
Taverns don't seem to help as far as i can tell so i say don't use them.
The best defense is a good offense, so get rid of the storehouse and build another barrack to train faster to defend your goods instead of hiding them. Put all of your resources and troops in one city and make em work for it!
If you like using the market(I personally don't have any) and your cities are in the same domain you are getting the same market, so get ride of some.
With the new barb raids food is pretty much not needed so its time to get rid of the fields or turn some into ore fields as you can get food, wood and stone from the raids.
As long as you got a couple of good "farms" (other people's castles) that give you ore though, you go ahead and get rid of all your fields. This allows you to get rid of more cottages, which gives you more barracks.
I have one cottage per a city, and nothing in my fields.