I think that Brenda and Steve would have been cute together for a short time. But, I don't think they would come close to what Brenda and Dylan had. B/D were each other's first love, as well as the great love of their life, and they had a strong bond that even survived Dylan going to Kelly and both cheating the summer before senior year. Their bond prevented Brenda from being able to move on into another relationship, Dylan to completely sever ties to her or be able to tell Brenda that he was getting married. It even sent him to London after the death of his wife. At least, that is what it seemed like to me. He needed to leave BH, I do not think it was coincidence that he ended up with Brenda. (I also think if his wife had lived, that the bond would have lead to the marriage falling apart and him going to Brenda.)
If I could choose the time that would have been best for Brenda and Steve to be put together, it would be right after Dylan and Kelly got together and Brenda knew about their summer fling. I think that Brenda being with Steve would have driven Dylan and Kelly crazy. Just remember, Brenda is Dylan's first and great love and Kelly and Steve were probably each other's first love as well. I think it would be justice for them to feel that pain as well, but I don't think Brenda and Steve would be together for that reason.
I think Brenda and Steve would have a fun relationship and enjoy each other's company. I don't know if Brenda would balk at having a sexual relationship with Steve though. On one hand, I'm sure she would be comfortable enough with him; but on the other, Steve kinda took sex too lightly and I think Brenda would see that as a turn-off. I guarantee that Steve would not have any problems in that area.
About the drama and the hearthache, I think she would get it even if it was with Steve. Like you mentioned, Steve had some flaws that would make him hard to deal with, wandering eye being biggest concern. Brenda could be possessive and jealous, Steve too flirty and fun-loving. It was going to make some fireworks, just different kind from Dylan. I also think that Jim would have had a problem with Steve; I think Jim just was not ready for his little girl to grow up. I think Brandon would be hesitate at first, the same way he was with her dating Dylan.
I did not see Dylan making it seem like his drinking and/or anything else was Brenda's fault. I think I know what you're talking about in that area though: when Dylan made it seem like Kelly was just the next girl he wanted to date after his break-up with Brenda because he hadn't told Brenda the truth. She even said that when she was told Dylan's choice and learned about the previous summer. What made Brenda feel bad while with Dylan was that she felt like she could not protect him from his problems, things that she was not supposed to take on herself, instead just support and love him.
So I guess it comes down to: I wouldn't have minded seeing Brenda and Steve together, but definitely not a long term thing. I can see them together more as a catalyst to bring Brenda and Dylan back together.
To me, there is no better pairing than Brenda/Dylan.