A tuxedo is not a dark suit. It carries satin on the lapel and down the trouser seam, and it is worn with a bow tie, not a long tie - a suit never is. If the invitation says black tie, that distinction is the whole answer.
Notch lapels read the most casual of the three and suit a daytime or semi-formal event. Peak lapels are sharper and standard for the groom. Shawl lapels, the rounded unbroken curve, are the most formal and the most classic choice for black tie after dark.
A cummerbund or waistcoat covers the waistband so no shirt shows between jacket and trouser - pick one, never both. We match the party's formality and the hour of the event to the lapel, the tie, and the waist covering, so you never have to arrive and guess if you are underdressed.
Renting makes sense for one evening. If you already know you will wear a dinner jacket three times a year or more, buying is the better value over time, and we will tell you that plainly even though it costs us a rental.
