Castle Bonuses: redundant or symbiotic?

[aldin]

Heh - my pleasure. When you're using resource heavy nations (Ulm, for example) Fortified Cities can be a major boon. You may find that some of the other options work well with nations that aren't quite so resource dependant - to take advantage of cheaper costs, faster build times and/or better defenses

~Aldin

[General Tacticus]

Finally, stupid as it may sound, I dream of a defensive realm, each province with it's own tower, as far as the eye could see. Would this be stupid, or prudent?

You better be ready to defend every single one of those towers, because if you don't, you'll find that the nasty neighbours suddenly has a base to build troops right in your territory, instead of having to ferry them over 4 or 5 provinces...
Better stick with a few strategically placed and well defended fortified cities, IMHO

[Saxon]

You may want to be aware that the fortified city is very expensive and time consuming to build. It is very effective, but the cost in time and money is high. I have played with both and found that you need to think carefully on that one.

Also, run a search under threads in my name (Saxon). I had a similar set of questions to you a few weeks ago and got some great detailed answers on how resources are distributed. The general consensus was that you do not want to build a castle everywhere. Try checking out that thread for more details.

[Arryn]

Originally posted by General Tacticus:
You better be ready to defend every single one of those towers

As a side note, it's been my experience that forts are attack magnets for the AIs. The AIs seem to prefer to attack forts over attacking nearby, often less well-protected provinces that have magic sites or high income levels (and thus would be a higher priority if it were a human rather than an AI looking at what's juicy to go munch on).

Just a few added words of caution, FWIW.