Here is a list of some trike details and options, with the pros and cons of each, to help you decide.
Tires basically come in two versions, the skinny and the thick. The skinny are better for fast trikes because they are smaller and lighter, but the thicker tires are better for landing in rougher fields or soft ground. For landing in soft fields or sand, the front tire is the most important to be thick because a skinny one can dig in and with the high center of gravity of the wing, flip the trike forward. Additionally, thick tires have less drag in soft fields. Additionally, thick tires to provide the benefit of shock absorption and are a good overall choice for trikes. The extra area that the fatter tires produce is usually worth the benefits of the thicker tires.
When flying a trike and getting some hours on it you will have to get new tires just like a car or if you somehow destroy a tire you will have to replace the tires. Checking to see about actually buying tires is a factor in your decision. Some manufacturers use specialty tires that are hard to get. Check to see how easy it is to order tires. The more available they are the better.
Some like fairings, others do not. Fairings are streamline and allow a faster speed and better gas mileage. However, they weight more and cost more. I personally like a fairing because you have a place to put stuff inside the cockpit out of the wind, it allows faster speed, keeps the wind off for colder climates and less fatigue for longer flights, and simply looks sexier/more modern.
For a look at options such as a radio, communications system, emergency parachute that should go on every trike, go to the accessories section to look at these.
Options for Revo
Here is a video that goes over options to help you decide what options are for you: