Hey, Gunner,
The 65W version will be more than enough for you at 60 degree weather, even for extended rides (this assumes, of course, that you have a good riding jacket over the liner). I don't even start using my heated liner until the temps drop below 35 degrees (F).
For comparison to longer rides, I did an extended 38-degree ride last year, and while I eventually turned the gloves on at about 30%, I never needed to turn on the jacket liner.
The Warm-n-Safe jacket liner I purchased (100W) is total overkill, at least for me. My coldest ride yet this year was at 3 degrees (F), and I only needed the jacket somewhere between 1/3 and 1/2. Keep in mind, I use the Warm-N-Safe TempTroller, which is not a rheostat; it provides 100% of the capacity for X percent of the time. So, with the dial set to about half, all 100W are delivered for about a second, and then nothing for the next second. Below 20 degrees or so, the gloves I keep turned all the way up, which means all 15W are going constantly to each glove.
The Warm-N-Safe stuff is available directly from them at
http://www.warmnsafe.com/. I went with them only because Gerbings didn't have anything over 65W, and I knew I would be riding in extremely cold temps, so I wanted the most possible. In hindsight, that was a mistake, since I never use anything over 50% (100W half the time) with the Warm-n-Safe. The quality of the build is higher in the Gerbings, but so is the price. The connectors for the gloves are better on the Gerbings, as well.
The rest of my cold-weather gear consists of a Tourmaster Transitions II Jacket, the quilted liner goes in below 40 degrees. I also use Tourmaster Caliber overpants, and don't need the quilted liner in those until the weather drops below 30 degrees.
Hope this helps!