Various novels obviously mention various assignments, too, although Memory Beta only name-drops the Antares from Simon Hawke's Blaze of Glory, and Diane Duane's Intellivore indicates the Pathfinder as another early ship. The novel continuity is biased by JM Friedman's storyline where Picard spends almost his entire career aboard the Stargazer, though.
As far as starship commanders in TNG go, a character acted by Patrick Stewart isn't out of place in terms of age. We saw few young COs, although admittedly we generally failed to see the COs of small ships, a couple of Mirandas notwithstanding. But we could assume that 24th century medicine puts aging on hold at middle age, not at youth (or else we would have much more of young characters overall); somebody looking like Stewart in his fifties and sixties might plausibly be anything from 40 to 80 and perhaps beyond.
Timo Saloniemi
As far as starship commanders in TNG go, a character acted by Patrick Stewart isn't out of place in terms of age. We saw few young COs, although admittedly we generally failed to see the COs of small ships, a couple of Mirandas notwithstanding. But we could assume that 24th century medicine puts aging on hold at middle age, not at youth (or else we would have much more of young characters overall); somebody looking like Stewart in his fifties and sixties might plausibly be anything from 40 to 80 and perhaps beyond.
Timo Saloniemi