Enchant and conjuration dcs with and without spellsurge... can get both 3 higher...just need a bard, litany, and to max out shiradi for joy. Could hit a 70+ conjuration if I wanted to. Will max out shiradi sometime and post higher dcs. I believe a human AM could hit a 73 conjuration.
Enchant dc: 59
Enchant dc with spellsurge: 64
Conjuration dc: 61
Conjuration dc with spellsurge: 66
Great, now people are going to be saying casters have low-to-mid-60s sustainable DCs (and be very vocal while not knowing what they're talking about). :P