If you reside in an area with an REI (or bike shops) test ride a few models. My DIY errand bike has a large rear hub motor and pedals easily, but you can decide for yourself what's appropriate. Your best bet is an LBS which carries Specialized, Trek or Giant bikes (and a Specialized model would be my choice). My bike rides fine, but hasn't had the wires shortened and "hidden". Surprisingly (to me), the rear wheel weighs about 18 pounds and so does the rest of the bike (without battery).
