PeaceBang has been promoting the alb as a solution for heat-stroke in the pulpit, but I can't agree so I'm back to opining what ministers ought to wear.
It goes back to the "judge's robe" problem. A Canadian friend and colleague said to me he couldn't wear Geneva bands because it reminded him of what judges wear. Which I think is a fair comment -- I got my last batch at a legal supply shop in London -- if you can look past the gigantic black gown that many Protestant ministers and judges also have in common. The customs of the law and the ministry are conservative, and roll back to the medieval universities. So too, the comment that ministers wear graduation robes. (Although the black gown, according to Percy Dearmer, is a clerical garment in its own right so may be the root of it all.) That's not so, we wear the dress of learned clerks (compare, cleric) but the point does hit close to home and people -- ever since the lovefest of Vatican II and earlier in some Christian communions and sub-traditions -- have been driving for something more universally and authentically (read, ancient) Christian to wear. In case you've ever been in a Episcopal church and saw a century-old picture of the rector wearing a black gown, and wonder why his successor doesn't wear one today.
A white garment, not black, is the ecumenical consensus, but the sartorial record is inconclusive. I've been convinced of this, too, and have stated as much in an old posting where I have rehearsed this at more length. And if I were in a parish, I would segue away from the (exclusive) use of my black gown. (As a place-holding habit, I wear a white shirt to Sunday worship. It is chastening to think a ninth-century Christian would more likely closer recognize an common white t-shirt as "properly" Christian than a Geneva gown or a suit.)
So what do we choose, if not from the Fruit of the Loom Ecclesiastic line? There are four options, if you count the white Geneva-cut gown, which I don't because its is a historical mish-mash and makes anyone who wears it look like the Marshmallow Ghost. This leaves the alb, the (long) surplice and the cotta; note the last two are variations on a theme.
The alb is really very old, its origins lost in time. It is the kind of tunic that draws part of its appeal from how common it is. It is white, long, with thin sleeves -- rather like a nightgown -- and is worn with a cincture. It would be worn in the Mass with the scarf-like stole, the poncho-like chasibule (or a cape-like cope), an amice, a small tied-in cloth to protect the stole from a grimy neck, and other gear not important here. (Modern albs often have various devices added in place of the amice, some quite hideous.) I don't really know what, if anything, a priest would have worn under the alb in ages past but a Google scan of Australian habits suggest swim trunks are common today in the summer months. Here's a picture of a modern Anglican priest in this vesture.
This is why I said at PeaceBang's Beauty Tips for Ministers blog that I think albs are innerware and suggest a half-dressed clergymember. That, and some of the less-expensive albs on the market, are made of thin material -- perhaps a desirable quality in summer -- and you can see the pattern of whatever you're wearing beneath.
To complicate matters, a creation known as a cassock-alb, a cassalb, or a unica has appeared since Vatican II. It is far more stuctured, often heavier but sometimes still translucent. At best, for thin figures, I think they look like what Marlon Brando wore as Jor-El in the Superman (1978). For those of us with less-trim figures, the effect isn't stunning, and that cincture creates a line I would rather not see on myself. I didn't like it when I was reading at an Episcopal chapel in my undergraduate years, and I'm a lot fatter now. A chasuble would create a better "line" but apart from the Abraxan liturgical experiments, Unitarian Universalists have never worn chasubles so it would be reaching to assume that's a sartorial fix.
Surplices, more smock-like in cut, became more common in the high middle ages; they were originally worn over (sur) fur garments, and in southern Europe, they became shorter, thus the cotta (Italian for short).
This is how the Catholic Encyclopedia (1911 edition, now in the public domain) defines a surplice:
A large-sleeved tunic of half-length, made of fine linen or cotton, and worn by all the clergy. The wide sleeves distinguish it from the rochet and the alb; it differs from the alb inasmuch as it is shorter and is never girded. It is shorter and is never girded. It is ornamented at the hem and the sleeves either with embroidery, with lace-like insertions, or with lace. The lace should never be more than fifteen inches wide, as otherwise the real vestment is necessarily too much shortened by this merely ornamental addition. The surplice belongs to the liturgical vestment in the strict sense, and is the vestment most used. It is the choir dress, the vestment for processions, the official priestly dress of the lower clergy, the vestment worn by the priest in administering the sacraments, when giving blessings, at Benediction of the Blessed Sacrament, etc.; in the last-mentioned cases it is the substitute for the alb, which, according to present custom, is worn only at Mass and a few other functions.
But this sounds to me more like a cotta, which are unlikely to be well-loved by most Unitarian Universalists. The lace . . . ugh, I can't say anything polite about the lace. Longer, plainer surplices -- perhaps with a bit of cut work or embroidery near the hem -- are better for cooler climates and cooler tastes. I rather like the ones with square necks. Here's a picture of the same Anglican priest in choir dress, which includes a long surplice. This is what I would suggest, knowing that the Vestments Controversy is or should be dead, even among latter-day Puritans like us. (As I've said before, the minister of the Mill Hill Unitarian Chapel, Leeds, makes it work.)
You would wear a surplice over a cassock, but I wouldn't blink if a clergywoman wore a surplice over a dress or skirt of the right cut and weight. (Not all cassocks are black, so I'm not even suggesting a black dress, but a big and bright pattern is probably out.) A surplice over pants, for women or men, I think is out of bounds because you would look like a stork: you need the cassock/skirt to give the surplice some loft, anyway.
Choir dress is always correct for non-sacramental worship, which for those of us lower on the churchmanship scale, is almost all worship. More, there is little differentiation -- collar and tabs, plus black scarf if anything -- between the clergy and other worship participants. I wish more choirs would wear choir dress: a better, more traditional look than the (ugh) jewel toned preaching gowns that so many churches have. And the sacraments? There is enough of a tradition to swap the preaching scarf for the smaller Eucharistic vestment -- the stole -- for communion and baptism, and leave the chasuble behind.
OK, enough for now. Feel free to comment.