When it comes to small planes, weight matters. Don't be surprised when your contact emails you for all passenger weights, and when the pilot organizes seating by weights. (You don't want the three biggest people on the right side, for instance.) Similarly, don't expect to bring two weeks of stuff for a weekend, and definitely mention if you're planning on bringing golf clubs or skis. If they don't fit, check out ShipSticks or LuggageForward, which sends your equipment beforehand for a relatively small fee.
Another place private air charter will surprise you – and save you time - is on the ground. These days flying commercial aircraft means you can sometimes spend as much time on the ground as you do in the air -- making your way through boarding pass and baggage check lines, working your way through TSA procedures, and struggling through plane boarding and overhead bin competition.