There are tons of things to consider about "how well" you might like being a flight attendant. It truly and very heavily depends on: 1) the airline you end up at, 2) the city in which you'll be based, and 3) whether you end up as a "reserve" f/a vs. a "line holder".
Each airline is different regarding corporate culture, fiscal stability, seniority sensitivity, importance of unionization, and most importantly, compensation/benefits. As far as the monotony of the job, it can get tedious. But unlike many other professions, this is one in which you can constantly re-invent it all the time by bidding on different routes, aircraft to work on and overall schedules (but ONLY if you're a line-holder -- reserves do not enjoy such privileges.) Also, as time goes on, the job seems to get better as you'll make much better $$$ and work fewer days of the month, not to mention better seniority.
Something else to consider is your toleration for working with the TRAVELLING public, which IMHO, is quite different from working in retail customer service. You MUST demonstrate leadership abilities, you MUST demonstrate physical agility, you MUST be flexible with your time, and you MUST be patient. Many pax seem to despise f/a's (and airlines in general) and do not hesitate in showing it. You will be physically tired, annoyed at unreasonable pax, perturbed at delays, but through it all, you MUST remain professional and keep smiling the whole time. (I know many f/a's do not do this nowadays, but at least you're supposed to).
As far as the image of most male f/a's being gay, well all I can say is that at UA, you'd be VERY, VERY, VERY surprised at how many STRAIGHT, MARRIED older male f/a's there are at this company. Of course there's a lot of gay ones too. But as someone pointed out, this is such a trivial issue. Afterall it will be YOUR career whereby YOU'LL be travelling free. You'll suddenly gain many 'friends' when they find out how many buddy passes you have to spare. --Don't worry about what anyone else thinks when it comes to your livelihood and what makes you happy.
Feel free to email me anytime.