In response to your mchs and ninjas.. they should NEVER hold on to cooldowns for "burst phases" unless its the hands in as3, and spear also affects mudra cooldown, allowing ninja to use another ninjutsu before the 20s mark, which is a dps increase no matter what angle you look at it.
If you dont have a RR youre saving and you draw a bole.. just throw it on the tank anyways. you can solo heal in that time so your co-healer can dps. you might not feel the effects, but theyre there. they help. no sense in burning too many cards, youre gimping yourself.
Ewer is immensly powerful, especially on summoners, or your co-healer. or yourself. More mana=more wiggle room, or for the summoner, if theyre good, they will realize you ewer'd them, and they will throw out extra ruin III. dps increase. if neither are applicable, RR fodder for Expanded.
Spire is considerably less useful, but if no DoW are hurting for tp, more expanded RR fodder. but as you said, your melee swap the gob, whereas if you threw a spire on your monk (who is much better aoe and single target damage than dragoon) they would be able to dps longer. dps increase.
all of your cards are dps increases one way or another, the more of them you burn on royal road, the more dps loss you incur. royal road and shuffle both should be used for strategic buffing, setting up for phases that require heavy dps, heavy healing, etc.
spreads go to arrow/balance first and foremost, or spear/ewer situationally. an expanded spear on pull is WAY underrated.
example: Youre on oppressor savage, .5 has yet to come out, you have an arrow on spread, no current royal road, and you draw a bole. shuffle is ready to be used, and a tankbuster is coming up soon.
your options now are extensive. you could toss the bole on the tank, and save the arrow for the next draw, hopeful for an ewer/spire.
you could shuffle the bole for a hopeful ewer/spire for some serious raidwide dps before .5 comes out.
you could royal road the bole and arrow a dps for a more reliable dps increase (because you wont always get expanded rr)
the strengths of AST is mainly in how many options it has, but making the wrong decisions is also a major weakness of AST. It has amazing potential, and you shouldnt downplay the potential of any of your cards. they are all very strong, albeit not always in the same ways.