A suit should be well-made and flatter the body. The use of a natural fabric from a reputable mill in a sturdy construction is never a loser (assuming some traditional variant in tailoring). The fit should flatter the physique, complimenting the assets or mitigating the liabilities.
Cuffed or hemmed? Personal preference.
Rise? Also preference, but one which requires some attention.
Lapel: A product of its era.
Button number: See above
Vents: Really? People actually notice this? I have center, side, and non vented (continental?) jackets.
My preferences? They are a factor of my age, what I grew up seeing as "fashionable", and my judgment thereof. I like an overall slim fit in my suits. I prefer a lower rise...it just feels more natural and comfortable than wearing a belt near my navel. Fashionable qualities thereof probably bolstered that sentiment. I also like my pants hemmed. With my body proportions, cuffs make me appear shorter. On a personal note, cuffs also scream (to me) "seconds/hand-me-down/couldn't afford a tailor." On my jackets, I prefer the look of the double vent. It works well in contrasting ideally broad shoulders with a tapered lower torso. However, there is a spot in my wardrobe for that beaten up "professor'ish" 100% cashmere non-vented sport coat. My style can and does incorporate "older" pieces, such as full length overcoats...which have fallen utterly out of favor with my generation.
I'm 21. Will I be working these characters in my suits when I am 40? Most likely. With my attitude, friends and family have acknowledged that my style "works" for me. The attitude will also work for me. In 20 years, come hell or this: http://www.styleforum.net/t/263999/new-ralph-lauren-black-label-wide-legged-jeans-opinions
, I will have my slim fit, low rise, double vents, slim-straight jeans, brown leather bomber jackets, full length cashmere overcoats, brightly colored (bordering on metrosexually prep) argyle socks, and hemmed trousers.
Here's a little secret. In 1830, 60 year olds were still kicking about in the fashions of their youth. Yes, that's right. They still had silk stockings and powdered their hair.
The message: Enjoy what you wear. Have the attitude to pull it off, if not perfectly in fashion. Go for quality. Pay respects at the temple of tradition where possible. Oh, and get off the fucking pulpit when dealing with others. Skinny tie God won't smite you for failing to convert a guy who loves his nearly 4 inch'ers.