The day Dilbert finally wears a long-sleeved shirt with his tie he will be destined for the Vice Presidental suite. Ties should reach your belt line. A tie badly tied and too short makes you look like a rube. Tie clips and tacks are way out of date. Trousers should be long enough to cover your socks, and socks should cover your shins even when you cross your legs.
Pants are long enough if they have a slight break over the shoe in front.
The Levi Strauss website has some good tips on this topic. One or the other please. And if you opt for the braces, please make certain they are the kind that fasten inside your trousers with buttons. It's very easy to have a tailor or the alterations person at your dry cleaners put brace buttons on your pants if they don't already have them. The metal clip-ons are for the guys who wear short sleeve shirts with ties.