I like that... city planning is always one I'm reluctant to go for but that might sway me
EDIT:
Also, another footnote - We're finding the limits placed on the trained animal units to be really making even having exp for those units fairly useless (and rather frustrating). I'd suggest at least opening up the Combat, Withdrawal, Field Fighter, Forestry and Guerrilla lines fully for them while keeping the terrain options. They would also serve pretty well with a lot of visibility expanding promotions as I use them as sentry units to wake up and alert me to new intrusions. First strike might be too advanced an idea for them as would any anti-troop type promos and the highly advanced Commando, Fanatic and such types. I've also been thinking they should maybe also have access to their own unique line, something I'll give some thought to as I go here.
Out of curiosity, is it currently possible to give a promotion to a unit that counteracts its opponent's chances of withdrawal? I can see animal units using such a promotion as they would be rather effective at tracking and chasing down troops attempting a getaway.