Male attire?

For churches and religous sites, long pants are usually required. Check with the sites you plan on visiting to check their dress code. For general walking around, shorts are becomming much more common, even in the larger cities. They are very common in beach areas throughout the country, but somewhat less common in some very small towns. Quite a change from 10-15 years ago when only a very, very few people wore shorts.

My husband is always hot and enjoys his shorts! I asked a friend who has a husband from France and has traveled in France and Spain a lot, and she said, whether we are in shorts or pants, we will be noticed as tourists! I guess meaning we'd never be able to blend in anyway. However, I am traveling to Spain in November, and I would be interested in those southern Spain churches that might require my knees to be covered?? Probably will just carry a pair of leggings in my bag.

Everyone, men and women, adults and children alike, should have knees and shoulders covered (and most of what is between the two areas) in every church or place of worship. This dress code is not always enforced at small churches, but it's best to be respectful. Remember, even though you are a tourist, the churches are active places of worship, not museums.
Also, especially in the evening, some restaurants may not wish to seat you in shorts; most won't mind.

It is very simple:
skip the specific places where you read and believe that shorts are frowned upon or go to those places but wear pants, very simple.

Get a pair of light hiking pants that zip off into shorts. Wear those on the days you want to visit churches.

There's this absurd notion -I don't know if it's the case here, apologies- from some visitors, especially from the US, that "they'll be spotted right away" wherever they go, but being noticed as a tourist has nothing to do -in most instances- with your attire or your appearance -much less where you come from-, it has to do with your attitude, the places you visit and how you move about in the street. Spain is one of the most visited countries in the world and has attracted migrants and expats from all over. A sizable chunk of its residents (hence, "locals") are foreign, and from all colours, races and shapes.

Thus, these days, especially in bigger towns and cities, it's nearly impossible to know who's local and who's not. These residents 'of foreign origin' are from different cultures and religions, therefore their attire, fashion tastes, and attitudes are also varied. Not even the language is a definitive tell-tell sign anymore that you're a tourist. The ONLY way you can spot a tourist without any doubt is paying close attention to someone and see what he looks at, at what pace he moves, etc. and yes, certain out-of-place fashion statements do help as well (albeit in cosmopolitan cities like say Barcelona or Madrid, that wouldn't necessarily mean you're a passer-by). I grant you that for those of us that are more observers it's easier to guess when someone is not "local", but one can never be 100% sure. Obviously, this is not to say that there aren't some visitors that, believe it or not, do indeed wear a "tourist uniform", LOL!.... those are easy to spot.

As per shorts, each city has its own "customs", so to speak. Thus, for example in Madrid (or in Barcelona) you wouldn't be wearing shorts to a dinner at certain restaurants -not necessarily 'cheffy' ones- nor would you wear them either in many venues, such (most) theatre plays or to certain nightclubs, just to mention a few occasions. In the vast majority is not that you won't be able to get in (albeit in some you won't, period) but you'll immediately feel out of place. But again, this wouldn't necessarily be so strict in other cities and in some, the approach is very relaxed.

As per religious buildings, this is a mixed pot. Starting from the premise that Spain is NOT a country -not in the traditional sense, that is- and that several cultures located in different geographical places co-exist here, it'll depend pretty much on where you are visiting that tolerance will be greater or not.

For example, where I am from, in Catalonia -capital: Barcelona-, there isn't, in general terms, such a great church-going fervor because the vast majority of people are either not religious at all, or if they are, hardly go to church. Thus, at the Cathedral in Barcelona -and at certain time-bands only- you'll be requested to wear shorts below your knees and have your arms (and torso obviously!) covered to get in to visit. Note this is not too much "enforced" outside these time-bands. However, I can't really recall other churches in which would have a problem if wearing shorts -and that includes La Sagrada Familia. But again, common sense applies: anyone wearing revealing tops or very short shorts would probably be asked to leave by the staff.

All of this, however, might not apply in say, Seville, among many other places. The Andalusians or the Castilians for example, have a deep sense of religion and not following protocol could be considered an offense. Again, I'm generalizing, of course, not everybody in those places is religious either.

If anyone is wary about this issue I suggest to put a pair of grown-up pants (=slackers) in your luggage and voilà, problem solved :))

My first time in Europe was on a high school trip in 1966. We were required to take a coat and tie and wore that to dinner most evenings. Times have changed.

I work under the same adage I use when doing a job interview - I'd rather be a little overdressed than underdressed. I consider being dressed properly as being polite to my hosts, therefore I tend to dress conservatively.

I also think, rightly or wrongly, that it is more appropriate for a 25 year old to wear shorts than a 65 year old to wear shorts. I agree with others, look at the region and your plans for the day to decide whether shorts would be acceptable.

Whatever you do, don't dress like the average Walmart shopper!

Other than in beach areas, yes DougMac, it is mostly the younger generations who wear shorts. I don’t recall seeing many in their 50s or older wearing them in the cities.

Bill: probably not paying much attention, because as you said, wear what you like.

BTW... if (if!) my post distilled otherwise, I didn't mean to impose any view/fashion, huh!.... I just shared 'a' view of this city by a born and bred local. Having said that, as anyone living in a big city (any big city) will confirm, there's never a uniform view about them, it depends pretty much about a bunch of factors (your age, your background, your circles, your values, etc.).

I value the freedom to do-as-you-please, and Barcelona is very laid-back in that sense, but there are also 'social habits' everywhere you visit and Barcelona is not an exception. Visitors, especially women -which seem to be much more aware of this, lol!- keep posting questions about attire in the forums, thus, I've taken the view of being rather a tad conservative in my responses and to inform about them as best as I can so no one feels "out-of-place" in any place he/she might be visiting while in my town.

But again, the only thing you legally cannot do in Barcelona, since this is not a beach resort, is to go around in the street in a bikini and/or with a naked torso -except for the boulevard by the beach and adjacent streets. That may (and does happen!) yield you a fine because it's against the City Code of Regulations. Period. Anything else goes -yet private businesses can equally refuse you entrance if they wish if your attire is way "too" casual.