Are undergraduate journals a good choice for publishing papers? I am 18 years old (high school undergraduate) but I have had my first scientific paper published by the age of 16 to a regular (non-undergraduate) journal. However, I am preparing some papers for publication related to Computer Vision, Computational Geometry and Scientific Software and, through a scholastic search at the Internet I found that there are some undergraduate journals that are often more flexible to what is being published since they contain undergraduate articles, as well as in the reviewing process.

So, generically speaking, are undergraduate journals a good choice for publications even for someone that has already published some of his work to regular journals? I know that it heavily depends on the content and the significance of the contributions being discussed in the paper but do undergraduate journals trigger the interest from other researchers to cite work and get informed from them?
Don't publish in weird journals 

Work to publish in the mainstream journals, despite their fickle biases and sometimes burdensome cost. Fields often have a pecking order of journals and the journal in which an article is published can change the perception of an article. Journals such as the national high school journal of science may be well-intentioned, but seem to provide a way for people to start worrying earlier and earlier about publishing.

It is premature for you to worry about your publication profile.

You've already published one paper at 16-- that's great. You are ahead of the curve. Graduate programs look for undergraduates to have published. Colleges look for evidence of potential. In the two labs I've worked in, the PI evaluates prospective high school students and undergraduates based on a letter of recommendations and a brief talk with the prospective student. Incremental publications in third tier journals may be a necessary part of the tenure slog, but you have the time now to just learn science and decide whether you want to pursue it as a career. Worrying about publications in high school is putting the cart before the horse.