That, in my own opinion, is your most important decision. If you choose the wrong bike, you will hate life. what kind of motor are you thinking about going with, 2-stroke or 4-stroke?.... 4 strokes need more room, but 2 strokes are sometimes too big for a bike too...... my best advice is to stick to a “basic” design.... there are some bizarre frame styles out there.... and more expensive bikes get pretty custom, and thus require custom installation methods.... good brakes are a plus.... I like hand brakes, coaster brakes are risky....
my suggestion is the Micargi Touch 7spd Beach Cruiser Bikes For Sale | Micargi Bikes
or if you want a super cheap bike that gets the job done and looks great try the Huffy Cranbrook at wal-mart (only 85 bucks)... www.broped.com
has an awesome one on their main page.... it’s the silver one at the bottom
Welcome and good luck!