I think a good pacing for resources might be, lessee quick number crunch
5 spaces in between towns
town1 ***** town2
^ 1 resource in between
maybe spread them out in 2 directions o you might not find it right away
15 x 15 area (12 x 12 =144, 15 x 5 is 100+50 +50 +25 = 225)
so in a 225 area square you would probably find (assuming 2 players starting in the area)
2 starting seeded +2 starting seeded + 3 inbetweeners which are random to fight over
+ those spawned by adventure tech (which would potentially be 2 food types + 1 mine type +1 crystal)
+ those spawned by diplomacy
the random ones would best be the wild horses/warg, shards, arcane, tech, materials
(EDIT: this adds up to approximately 20 resources, which ends up nearly to 1 resources every 10 squares which might actually be pretty close to the experience i have playing on ridiculous - so yeah, this fine tuning is a little twitchy, you want just enough to fight over but not enough to make it a cakewalk)
and you need to decide how much mana generation (ie total number of shards) you want per 225 map area with a total of at least one of each type for people to fight over in order to cast master of magic spell
side note: i think the entertainment portion of the civ tech tree would be interesting to have an extra effect that unlocks information about the other factions, rather than being able to look through all of their stuff simply by clicking on it. Have and equivalent function tied to the arcane school system/ shard upgrades where your arcane staff provides info on the arcane might of your opponents including types of shards controlled and progress other s have made on finding teh spell of mastery - which should set off alarms bells when cast so people try to stop you from winning the game
Adventure tech should unlock info on the notables and hero strengths available to other factions as well as showing their progress towards winning the game in that manner, you need to know if you have to hunt down their heroes so they can't win the game that way.
It would be a riot to get the message "you lose, Gilden cast the spell of mastery and you fled for your life as your magic is drained away" completely out of he blue, just as you were about to pillage the countryside with your army of doom - you'd think you were a complete chump and had been taken by the game.
might be neat if the civ tech let you built a wonder of the world that inspired uprisings of the peasants against their sovereigns making it easier to take all their cities - maybe a percentage chance that they revolt to your side that increases every turn to a maximum number (25% or something)
(EDIT Number 2: One the one hand i would say you should never have 2 of the same resource beside each other because it seems to break the system and encourage steamrolling - On the other hand you have it set up so that you can build as many of the same type as you want for basic building so having the twin resource there really only saves you 15 population and 3 or 4 gold per turn, plus some spare change in materials or gold in a lump payment which in the long wrong isn't that bad - it's a just a big shock to suddenly have 10 tech or 10 arcane research to churn out some quick tech or spell advances)