There are three basic types of electric bikes, and they are very popular in Ontario due to not needing a license to drive, while you do need a special license for a little gas engine scooter. You have the add-on type, the bicycle type and the scooter type. Each has advantages, each has disadvantages. I immediately think of the scooter type, since that is what most people have where I used to live. Examples: http://www.scooteretti.com/ Note that even the scooters have pedals, making them technically a person-powered vehicle, hence the no license required. In Ontario if you remove the pedals it then becomes a motorcycle, believe it or not.
Range is the big question, and that comes down to power and weight. You need to investigate the weight carrying capacity of the bike and get one that suits your personal needs. The light "bike" type units have a big advantage in weight but usually have smaller batteries to take away that advantage. Power in the battery is key, so look at the voltage of the battery and it's amp-hour rating, multiply the two to get watt-hours available and remember that you need to use around half the available to not harm the battery.
I think they are a great option, but can be very pricey. http://smartdirect.ca/smart-electric-bike
Brian