Rogue shows up in a cameo in 170 and joins in 171. In 172 she then immediately goes on an adventure with Wolverine, who initially hates her, that lasts the next few issues. Or course, Claremont peppered Rogue's transition from villain to real hero out over about 100 or so issues, so joining the X-Men is far from the last interesting thing that happens with her.
I like the X-Men in the 80s quite a bit, myself. The grittier Outback version that came about after the Fall of the Mutants is my favorite version. Except for a couple of issues any X-Men comic from around 170 to 300 can be had for just a couple of bucks, in fact I paid a dollar for most of mine, so collecting it is not a huge challenge.
Here's the deal, I'm the best there is. I wake up in the morning and I urinate excellence. And nobody can hang with my stuff. I'm just a big hairy American winning machine.
I'm very humble, too.