Keep in mind that most pure sportbikes don't make an abundance of amperage and they're only designed to barely keep a charge on the battery so it's best to have the fewest connectors (minimizing the risk of corrosion or voltage drops due to poor plugs) and draws on their battery.
A relay is a good idea for keeping the circuit live only when the key is ON, but the relay itself, depending on it's size, may draw more than you'd like. This isn't a big deal for a lot of bikes but keep in mind sportbikes will fry their charging systems if you look at them the wrong way! Check the amount of current that the relay takes to operate. For the cigarette lighter I put in the tail of my GSXR, I used a connector from the battery tender pigtail wire that I put in before. It is bolted to the battery side of the starter relay, so the connection is never disturbed and it has a 10 AMP fuse. The other connector that matches the battery tender pigtail is plugged in and has an "in line" fuse holder that I've installed a 2 AMP fuse in. Under no circumstances do I want that cigarette lighter to pull more than 2 AMPS from my battery, so it will blow if it does. I'll probably get around to putting a switch in the circuit at some point. I am out in Scarborough if you want to come by and learn more.
