I make a 60 mile round trip commute on the Versys, have done so since last spring and I ride in the rain and cold, pretty much so long as the morning temps ar 30 and above I ride. (below 30 I worry about black ice).
For me the key items were a cover and luggage able to hold my brief case, cover and shoes on the way to the train station (I commute by train into NYC) and hold my jacket, pants and boots while I am at work. I also didn't want to spend a ton of cash. I ended up getting Givi E21 side cases which work great to hold my jacket and boots and a Givi E45N cheap top case which holds my helmet and riding pants.
Works perfect for me and the cover keeps eyes off the bike. I haven't ever once used a disc lock or locked the cover, but if you are worried a disc lock and cable for the cover are a good idea. (you route the cable through the eyelets of the cover and connect the cable eyelet to the disc lock on the disc.
I have three sets of gear, mesh jacket and pants for the hot weather, fully waterproof jacket and pants for the cold and wet and rain gear to go over my mesh. Usually in the summer I just keep the rain gear in one of the bags as a just in case. I also have a variety of gloves, Gerbing heated, Held street gloves (my favorite) and Rev'It winter/waterproof, it is worth having the right gear for the right condition. Same with my boots, I have Vendramini shorty for the summer, Sidi full sized for the cooler weather and Sidi waterproof boots for the colder weather.
I have accumulated my gear choices over many years, and while I upgrade my gear every few years, the basic options are the same.
I also invested a long time ago in heated grips, heated gloves and a heated jacket liner, for commuting they have proved invaluable especially in late October/November around here. Oh and I keep a hair brush in my top case to fix my helmet head when I get to the train station, don't laugh, it makes a difference and worth the thought.
Finally since I often leave at 5 AM when it is dark and live in the country of sorts, I swapped the low beam for an HID. A lot more light, but does not bother on coming drivers or drivers I am behind, also leaves me the high beam as an instant on (HID takes a bit to warm up and get fully bright) for flashing, etc.
Just remember, the thing about commuting is having a system/routine and giving it time to get it down right. At first commuting seems like a bitch, putting the gear on, taking it off and stowing it, putting it on again when all you want to do is go home. But I have it down to 5 min each time, in the AM, at the train station and then heading home, so while it adds time, the ability to ride my bike everyday and getting 55 MPH over my 18 MPG truck is all good.