CL601 is probably not a bad match for that flying profile. Falcon 50 if you feel the need for three engines and can accept a smaller cabin. CL604 if the age of both of those put you off (a little bit overkill though). All can be had for less than $6m.
Hawkers are pretty much bullet proof and would be an ideal match were it not for the fact that with 8 people it's a bit of a squash. Falcon 50 and CL30 gives you 6 individual seats rather than 5, making the sofa mildly more tolerable for long flights.