I shadowed perio before I started school, it was pretty interesting, as Perio is a very surgical specialty. I remember sitting in on multiple surgeries in my one day of shadowing with him, haha.
You better not be squeamish with blood ; ). Many surgical procedures from soft-tissue grafting to implants to sinus lifts etc. If it seems like something you'd be interested in, go for it! I'm guessing you've already done Endo and Ortho so if you weren't ecstatic about Perio, I would say to go shadow pediatric dentist or possibly a prosthodontist, but prosth is also surgical (but not as much as Perio)
I shadowed a perio and got to see a gingival graft, a connective tissue graft, and several implant procedures that were pretty varied.
I thought it was a badass experience, and would highly recommend it! The procedures were fascinating, and (though this might have just been the perio I shadowed) everyone at the office had a cowboy attitude and a dark sense of humor which massively appealed to me.
Perio is pretty awesome. It's very very technique sensitive and requires a lot of skill for very good results. It's pretty awesome to watch. If I were to specialize, perio would be top 2 on my list.
Think of it this way. Perio thinks in mm. Oral surgery thinks in inches. (Not my words)