Hanzo04: "could someone from the Bujinkan be so kind as to tell me how a regular class goes. I mean from the beginning to end. etiquette, techniques,discussions, dismissal everything you can think of. and do you guys work on the really traditional aspects of the art like the usage of the traditonal tools and weapons? thanks a lot."
Mine is pretty standard. Before class starts, we'll be chatting and stretching and such, then we bow in and do warmup exercises. Warmup usually consists of many repetitions of sanshin, but sometimes there'll be some junantaiso first before that.
After that, or sometimes mixed in with the sanshin kata (if there are similar principles to work on), we'll do various drills: one day it'll be punching, another kicking, on another rolls, others will be walking or jumping or something.
Then, we'll do a couple forms, usually from the kihon happo. Each class usually has some weapon applications as well.
Then we bow out, and have a question and answer period followed by announcements of upcoming events like seminars and such.
Not every session is organized like that though. Some are completely random, just whatever shidoshi comes up with on the spot (I suspect that it depends on who is at training that day and how things that we do lead to other things).
We often work with traditional aspects like katana, bo, shuriken, stealth, etc. (wouldn't be ninjutsu without it, right?)
Kreth: "This is rather vague. A lot will depend on your instructor and his/her teaching style."
This is true, each Buj' school will have its own flavor, but if you train in enough dojo, you'll notice many similarities.
"Personally, I prefer a fairly informal class. We have a bow in at the beginning of class... Most etiquette is common sense. Don't talk when the instructor is talking, be respectful of the dojo and training equipment. At the end of class, we finish with a bowout."
I enjoy both formal and informal classes. Totally different vibe, but both a cool experience. Most Buj' dojo I've been to though (no, wait, all of them) have been mostly informal (of course with the common sense courtesies and respect). We don't place much emphasis on wearing the proper uniform (or any uniform at all), talking and joking around is o.k. as long as we're kicking eachother's *** while we're doing it (i.e. standing around and chatting when you're supposed to be practicing is not allowed). We'll often have music playing in the background. I've trained with at least four shidoshi over the years, and none has demanded to be called by any title - all first name basis. I get the feeling that instructor and student are peers, with Hatsumi being sensei to both, so both treat eachother as equals.
MisterMike: "So how long is a class?"
Most are two hours, some go longer. Weekend seminars can be four to six hours.
Nimravus: "Usually, tough training means that you have a hard time getting up from chairs and opening doors the next day..."

ohhh yeah, those days. . .
Like when you look in the mirror, "huh, where did that bruise come from? I don't remember getting hit there.... or there.... or..."