If you desire to have an aircraft capable of flying a 3,500NM trip, do not purchase an aircraft with an advertised 3,500NM range. Purchase one that has at least a 4,000NM range or more. Personally I would recommend at least an advertised 4,500NM range.
The reason is that the advertised range of any aircraft is the most optimized range that the manufacture can make. It is derived by using average historical winds, very good weather and computer models. In real life one very seldom encounters those conditions.
Also, if you are not going to be the Chief Pilot, I would recommend hiring a chief pilot prior to the purchase. Ideally one with experience in the types of aircraft that you are considering and use his knowledge and experience in choosing the best aircraft that will meet your expectations.
Also, as someone else here suggested, hire a dependable independent aircraft broker to assist you. They usually can recommend some pilots for you to interview.
If you are going to operate from any high altitude airports that has high temperatures, I would strongly recommend the Falcon 900EASY. If not, just add it to the list of aircraft to consider.
I wish you good luck and have a good time selecting the aircraft you need.