A serious question came up recently. Is the midnight Paschal liturgy to be considered a daytime event or an evening event for the purposes of dressing? On the one hand, it is midnight after all. On the other, it is, liturgically, day, sort of.
Practically, this is the question of whether one has occasion to bring out the dinner jacket (tails would seem a bit much) or whether one should stick with a suit (no American has formal morning attire, but if one has a black peak lapel jacket and striped/checked trousers, one could sneak something by the unsuspecting masses, while a morning coat would just be too much).
I'm not going to suggest that one hire or purchase such clothes for the occasion if one doesn't have them, except to say that every man should have a suit. Nor am I suggesting that we turn the Paschal vigil into an ostentatious display of finery. This is, largely, academic for me, since I don't have a dinner jacket and don't intend to purchase one. I wouldn't wear one even if it were appropriate because I would typically serve and a black bowtie doesn't work well with a sticharion (nor should altar servers wear ties, in my opinion). I've already detailed my opinion on formal daytime attire. Accordingly, my Easter attire is already chosen for me no matter what: a dark solid-colored suit (striped suits are strictly business attire). I'm going with oxford grey.