Frag #01 -- Afterthought: Both fragments give examples (amplification?) of "places" in the preceding main clause. Thus, all three could be combined into one -- "On the way down to Florida we passed some really neat places, like a place called South of the Border, and the place Vanna White is from." Many people would also accept a dash after "places." The resulting main clause, however, contains 27 words, which is over three times the average for the passage (8.0.), and more than twice  the longest main clause in it (13 words). This large difference in length is what makes me categorize these fragments as afterthoughts.The student's working memory was probably only able to handle the first main clause ("On the way down to Florida we passed some really neat places."), which itself is twelve words long, or 1.5 times the average for the passage. Having gotten that sentence down safely, and ended it with a period, the writer added the two examples.
     If I were this student's teacher, I would simply ignore these fragments. If this student were being taught using the KISS Approach in ideal circumstances, as a seventh grader, she would be beginning the analysis of clauses. If this writing sample were part of a class statistical analysis project, the student would see that she averages 8.0 words per main clause, as opposed to the class average of 9.4. I would use that as motivation for some sentence combining exercises that emphasize subordinate clauses. The student might even be asked to do it using this writing sample -- "Then we went to Miami Beach where I got stung by a jellyfish twice." Such exercises would increase the student's STM processing capacity, thereby preparing her to handle the longer main clauses.
      If the student were analyzing this pasage, she would find the two fragments. In that case, the teacher would have three options: 1) show the student various "mature" 27-word main clause variants, 2) show the student how to simplify, or 3) show the student both. What I would do would depend on my estimates of the student's intelligence and frustration level. Simplification would involve the elimination of advanced constructions -- "One place was called South of the Border, and the other is where Vanna White is from." This changes the gerundive, "called" back to a full finite verb. It also eliminates the potential appositives -- "On the way down to Florida we passed some really neat places, a place called South of the Border, and the place Vanna White is from."
     These fragments -- and this text, by the way, demonstrate why I try to tell middle schooll teachers that they should be very careful about trying to teach their students to use advanced constructions such as gerundives and appositives. Showing this student how to put more gerundives and appositives into her writing will probably result in more errors. What she needs first is some work on combining clauses. As it is, she has already demonstrated excellent use of a left-branching gerundive ("Going"), which, whatever else I did, I would point out to her. (Only two of the thirty-one samples include left branching gerundives. See.) I would also point out to the student that "The fragments involve advanced constructions which you will learn about in later grades." There is a big difference between trying to teach seventh graders to recognize and/or use such constructions (which will probably only confuse and frustrate them) and telling students that their writing includes advanced constructions, or that their errors result from their attempts to use them. The latter sends the message that the students are not bad writers; they are advanced. Positive image is important, and in cases such as this one, teachers can honestly confer that positive image.
Frag #02 -- Afterthought: See # 1.