Now that the standard tux has been thrown out the window and replaced with several different options to fit the overall theme of your big day the best advice is to get a tux that fits your body type.  Here are some ideas, given different body types:

Short, stocky guys.
Jackets with slim shawl collars are a good bet.  You don’t need any of those broad-shoulder euro-style tuxes; that would be overkill.  Instead jackets with natural shoulder lines are best.  For pants, avoid styles that have too much break on the foot (can look sloppy); instead, try reverse double-pleated trousers.

Short, slender guys.
Skip the double-breasted styles and look at single-breasted jackets with a low button and wide lapels.

Tall, slender guys.
These folks have it easy—just about everything works.  Double-breasted tuxes with those euro-style broad shoulders are fine, as are those hip three-button styles that close high on the chest.  Trousers can have more break at the foot.

Tall, stocky guys.
Jacket length is a tough one here; try styles with shawl collars.  Consider a jacket with a bit of room to allow for movement.

Other tips:
Vests are a popular alternative to cummerbunds these days.  Be sure to ask whether the vest is a full back or half-back (full looks better if you take off your jacket during the reception).  Fit is important—look for a tux rental shop that knows how to measure properly (it is more than just a jacket size, shops should also take your inseam and waist measurements).  Insist on a fitting BEFORE the wedding to avoid any day-of surprises.  Also, pay attention to the fabric, 100% wool tuxes are best, but there are differences among wools.  Have a tux retailer show you the difference between a tropical wool fabric and other options.

Photos from GonnaGetWed.com member, Tip Top Tux