I intend to put something up on this in the next week or so but there are some interesting subtleties to Druid AC advancement.
Firstly, its easy to write off the single attack ACs (such as those with Bite or Tail attacks). Actually these get much more effective at 9th level when they get a second attack through Multiattack. Also, in general these attacks are more effective when the creature can only make a single attack in a round as they tend to deal more damage. This comes into play more often than you'd think and is further enhanced by buffs such as Greater Magic Fang and Haste which favour attacks with more damage from the primary attack.
Tyrannosaurs are king of the DPR tables past 8th and that’s even before adding in Animal Growth which makes them true beasts....
The dinosaur ACs are in general pretty interesting actually and, although in general a little more fragile than their mammal counterparts, tend to have much better natural armour.