Since I believe I am the person that informed EL that women like reading M/M I supposed I ought to respond to this...
I'll admit that I like to read about things I probably wouldn't do for real, but I won't be more specific than that, because it is a rather personal question. But in general almost any well-written erotic story can get you "hot" even one with just kissing. It's all about how the writer makes you feel with good imagery and sensations.
The idea of the feelings the writer can convey is more key to me than the actual sex acts. A good writer can make something I'd never consider very exciting, or something seemingly tame, like a kiss, can become much more.
I've worked with some new erotic writers who feel the need for the characters to always F*** and one person who had never had sex wrote something quite unrealistic and probably not very enjoyable. Her excuse was she never had sex so how could she know? I told her to work with something she could describe, even kissing can be very sexy if you write it to make the reader feel we are being kissed...
Well, sorry I went on a bit of a tangent.
That's more about the actual erotic elements.
In terms of an erotic romance or romantic erotica, the characters and the story need to be spot on. I don't care what they get up to in bed (or wherever) if the writer hasn't convinced me that these two people belong together, and that's for any gender pairing. Great sex scenes cannot resuscitate a crappy storyline, though I believe some publishers might not agree with me. Most do, however, so just a string of sex scenes need to make sense for the story.
Much of erotica written by gay men is more about the sex and less about the relationship. In a lot of cases there is no relationship especially in shorter pieces. There is definitely a different vibe in what I've read compared to women writing, though it definitely does not describe all. For women readers I think the relationship is important, and you need to make both characters ones the reader would want to know and have sex with.
Back to writing... I'm female but I write M/M. Obviously I have no personal experience of much of what that entails, but I have done research and I ask gay male friends questions. I have them read what I've written and let me know if something wouldn't work or might hurt. But it's really gratifying when they tell me reading my stuff gets them hot, because it means I've done a good job.
I admit that one of the reasons I don't write het is because it is almost too personal. I would feel everyone is expecting that I've done that and might judge me. So, M/M is a somewhat safer exercise for me; no one would ever wonder if I've actually done it
Hopefully something in there was useful.