Hi, K.. I have used tampons since I was a teenager also, and like another mom, I have gone swimming, running, weight-lifting--you name it--in them. I was actually a cross country and track runner in h.s. and college, so wearing a pad with shorty-shorts was just not my cup of tea, hence the switch to tampons. Anyway, I would choose a plastic applicator for now, as they are the most comfortable to insert. They also make cardboard applicators (Tampax, I think) that cover the cotton tip of the tampon, and those are easy, too. I would avoid the ones that have an exposed cotton tip, especially if your flow is light. They can just feel dry on insertion. (Eeek, just thinking about it makes me squirm.)
Also, make sure to change your tampon every couple of hours, especially on light flow days. Toxic Shock Syndrome (TSS) is very rare, but I did get it from forgetting to remove a tampon on a light flow day (had a track meet and forgot all about it). I got TSS, and it nearly killed me (no joke). That is not to scare you. I just feel compelled to remind people to change every few hours.
Hope you have a great vacation.