Go for the Citation 5 it has the power to get off quickly and the best slow flying wing of the citation range.
I disagree respectfully - Seen Vref of 92 knots on a 680 touching down at a little over 80, you've got 4 carbon brake packs from the Citation 750 and the Max land weight on the 680 is from memory 4000lbs less than the 750
Flown both - flown accurately and light the Sovereign can get stopped in a little over 350m and be wheels up (not 35ft) in a little over 450m.
I'm not a fanboy of the 680 lord knows it has its problems but to go a long way from short runways with modern avionics and a stand up cabin theres not much that can keep up - sure a 900 or F50 would be good but ones 20million US and the youngest F50 is probably knocking on 15 years old now - some owners just dont want to fly around in old equipment