You are best off to contact members of the LGBT clubs at various b-schools.
As you may or may not know, there's a huge but subtle difference between being *tolerant* and being *accepting*.
Virtually every b-school campus is tolerant (every school has anti-discriminatory policies, will talk about it being okay to be out, support of the faculty/administration, how the recruiters don't care, etc), and virtually no one will make an issue of your sexual orientation at least to your face or on the surface.
And as you probably would've guessed, while every b-school environment is tolerant and will be on their best behavior, some campuses/regions are simply more accepting than others when you go beneath the surface.
Also, it will vary not only from one school to the next, but from year to year. Not just based on the vibe from your straight peers, but from the LGBT students themselves. In any given year depending on the size of the incoming class, you're talking about 10 - 50 people total across both first- and second-years (not including faculty members and/or straight supporters). With a small group, a few people can make a huge difference.
Again, you'll get much better insight by contacting LGBT MBA students via their club websites, and have them talk to you off-the-record about what it's really like at their school vs other schools.
In the meantime, I'll give you two examples to show you how communities can be vastly different based on their website alone:
You can't judge how LGBT friendly or active a school is by their LGBT club websites alone, but it can be at least a start. Look how HBS tends to focus on coming out (making it clear that most are out, but it seems that not everyone is comfortable coming out to their classmates which may be the case at every school but to say it out loud tells you something), mental health issues/counseling, etc. may suggest something about where the LGBT community is at in that b-school environment. The HBS LGBT website is all business, a bit staid (honestly the website design is antiquated), and gives the impression that it's not much of a social/cultural/political thing.
Now contrast that with UCLA (or Kellogg) -- there are photos of social events, a much more personable "bio" section of the club officers, and so forth. The design and website copy is more relaxed, informal, and personable - giving the impression that the community may be more comfortable being open (not surprising since it's in California, which is arguably the most accepting of the LGBT community in the US).
Or compare Wharton vs. Columbia, or Chicago vs. NYU. Wharton and Chicago seem a bit more reserved and less open, whereas Columbia and NYU seem much more forthcoming about their club events, officer bios, photos and so forth. That can at least give you some initial impressions - maybe not about how accepting the rest of the school is, but about the culture of the LGBT organization itself within the school.
As for recruiting/companies -- while banks are tolerant, consulting firms tend to be more accepting. In industry, consumer products, media/entertainment and healthcare tend to be the most accepting while most other F500 are tolerant (and while I don't know off hand, but I'm sure oil & gas isn't even tolerant).
Kellogg, UCLA, Columbia and NYU seem to be the most accepting and/or the LGBT clubs seem to be the most active and social.
Go through all the LGBT websites (most will have links to the websites of other schools). You'll see that some will give you the impression that it's merely a *resource*, whereas others will give you the sense that it's a *community*.