I myself would use the 500w 36v hub motor, not because of range but because the motor is closer to 1hp (750w=1hp in case you didn't know) and the little extra power is welcome always.
I agree with Stan in that there are many factors in determining range. Since you will be using lead-acid batteries temperature plays a large role as well.
SLA simply do not work well when the temperature drops below 60. But since you live in Florida this probably isn't a very big concern. Usually the warmer you can get these batteries without them melting the better they work. and your range will get better.
Tires believe it or not, play a role here as well. Narrow tires with smoother tread offer less rolling resistance and again range is increased. Rim size is somewhat of a factor but not a huge one. Smaller rims are easier to start spinning but top speed is affected and coasting is down as well. Larger rims are hard to get spinning but coast better and top speed is increased.
Weight is not always a bad thing. Remember physics class. Mass in motion tends to stay in motion. If you thinking of using 3, 12v batteries it probably will add around 30lbs. More or less that's just an estimate.
I hope my ramblings have helped
