I live in a small city neighborhood.  Apartments, a corner store, a laundry-mat, a tavern and a mixed population.  Old and young. Singles, couples, not a lot of kids.  We're all kind of transient (except me-I've been here forever) waiting for better or different jobs or to buy a house or go to a nursing home.  Some of us are educated.  None of us have much money
There are a number of same sex couples who may or may not be gay. They live here.  Nobody seems to think its unusual.
Of course, most of us in this neighborhood have probably seen lots of things scarier than gay people. 

Are many people really only happy with gay couples as long as closed doors remain closed?

Is 'closed doors' code for sex and/or romantic behavior?  Because I don't want to see the sexual behaviors of ANY of my neighbors--gay or straight.
We are not pretty people.

Houston has a population of people from every where in the world and Houston has always been a working town.  People here are concerned with doing good work and succeeding at what they do.  Our mayor is a gay woman and no one thinks anything of it except maybe a few rednecks.  A gay couple bought the house next door and I couldn't be happier about it.  They are respected professionals in our community and first class folks.  One of the girls has agreed to be my surrogate sister and the other is my pal.  They are as proper as can be.  My neighborhood is bounded on one side by Rice University and on another side by the largest medical center in the world so excepting myself everyone in the neighborhood is pretty intelligent.  So, everything is cool here.  

I'm from a sort of 'No sex thank you, we're British' generation.  I buy into Linda's preference not to see other's sexual behaviour.  What two consenting adults do for one-another to gratify their libidos is entirely up to them.  
 
I am generally sympathetic toward gays.  A person's sexual preferences are not generally a matter of choice but rather of what they are, but one of the more memorable and dare I say it, offensive sights of my life, was the sight in a shopping mall of a flamboyantly dressed, load-mouthed gay man who was so 'camp', I think the expression is, that he was just plain offensive and more than a little bit unbelievable.  Any woman who dressed and behaved as he did would be regarded as more than a little odd, indeed almost sluttish.  I almost went looking for the candid camera
  
I look forward to an era when a person's or a couple's sexual preferences are a matter of general indifference to all except those directly involved, where to be gay is no longer to be a member of a discriminated against minority group who need special treatment and consideration, but just to be normal, nothing special, just like any humdrum heterosexual person or couple. 
 
But all of this is about my attitudes.  As to other's attitudes, I think we have come a long way and the few gay couples I know are generally tolerated (that is to say, ignored like any other couple) and are not discriminated against, but if they ever started 'making out' in a populated public place they would probably be regarded as behaving offensively, but probably no more so than if a heterosexual couple did the same thing.
 
I don't think we are anywhere near that era I look forward to, but we are getting there, I hope.