Like I said, that's not really how things in AWS are. The 1-11-475 has much more range (130nm more, >+10%), and there's nearly no difference in fuel consumption between -300, -400, -475 and -500, but -475 consumes 20kg/hr less than -500 (which consumes only 20kg/hr less than -400 and -300). This doesn't make it to a bad aircraft, but as you Miami based know 1480nm aren't much.
(aircraft, pax standard, pax maximum, pilots, crew, speed kts, range nm, fuel kg/hr)
BAC-1-11-475 75 89 2 3 35 409 1610 2370 Medium
BAC-1-11-500 100 119 2 3 35 409 1480 2390 Medium
Douglas DC-9-30 100 119 2 3 35 440 1360 3430 Large
I agree to nearly all of your points. BAC 1-11 is ok for most airlines, but I prefer B737 because of range. In Europe etc. I'd always go for 1-11, but however I see no point why going for DC-9 except the - maybe - short queue. The only advantage to the B737 is the higher speed, but I don't think this is a major point.
Boeing 737-200Adv 120 136 2 3 35 413 1670-1940-2050 2730-2790-2890 Large
Forget to say. DC-9 is much cheaper than B737 and BAC-1-11s are also much cheaper than DC-9. In my plans I haven't thought about limited money. So if you are short on money, things might change.