Fossy is right, do not forget to check the papers if the aircraft was privately operated, for comercial it is an other story...
You have to check what you want, like cabin height, usable seats acc. trip lenght, TO and LDG perf.according elevation of typical envisaged field and maintenance costs.
Excel is nice for the cabin and luggages, Hawker has less space than Excel for bags...Sovereign is the best!