Seek 3 appears to be an excellent choice. A triple up front with lots of low end hill climbing ability. I see that you're in Oregon. Disc brakes here in the Pacific Northwet (I'm in Olympia, WA) are an excellent choice. I've been commuting on a Kona Dew since 2008, and upgrading to the next Kona model up with disc brakes is the one thing I would have changed, if I could.
Fenders are essential. In my view, one can never have too many lights. I have ten on my bike, plus one on my helmet. Get at least one rear red flashing light, and two front white lights--one to be used flashing and one to be used solid. Batteries can die at the most inopportune moments, so two rear red flashing lights is good insurance against being without any rear light. A helmet protects one against lots of injuries, but it certainly won't save you if you need a tractor trailer head on. Riding glasses, particularly in the winter time, are needed. Don't rely upon cheap, inexpensive safety glasses as they will fog up and become useless. A product called Cat Crap--yes, that's really it's name--is one of the best anti-fog eyewear treatments on the market.
If you would please, update your post with the tires on your bike. According to the Giant website, the 2014 Seek 3 comes with Schwalbe Big Apple tires. If so, they appear to be an excellent choice for commuting. Tires that came with my Kona were very soft and puncture prone. After switching to Kevlar tires, I had a much happier commute.
A decent riding jacket in a highly visible color keeps the rain off, helps to make you visible to others, and will provide a good balance of warmth and ventilation in this mild climate. Rain pants are really all one needs in addition on rainy days.
In 2008, my commute was 2 miles over flat ground, and I was 41 at the time. A few weeks into it, I was pretty worn. Had to start riding every other day for a few weeks before I was able to comfortably ride every day.
In 2012, after a new job and a move, my commute fell to 1.4 miles; however, a modest uphill component was added. Kicked my backside for a while.
I also started riding with the local bike club once a week. Rode a 10-12 mile ride on a Sunday, and at 45 I thought I would die. Kept riding with them, and by the end of the ride season I'd ridden a number of longer rides of between 25 and 40 miles--plus one 68 mile ride. In 2013, I rode even more, including two 80 mile rides. In 2014, I rode my first two Centuries (100 mile rides).
Check into the local bike clubs. Going out just once a week, for even a short ride of 10-20 miles, will do wonders in making your 7 mile commute a breeze. I must warn you though, it can simply be feeding an addiction, but I can think of worse things than a cycling addiction.
Since your ride home will be uphill, look into the local bus service. Perhaps you can split your commute between the bus and your bike--particularly if you can ride the bus home, uphill, with your bike on the front rack of the transit bus.
Read up on Sheldon Brown's lock strategy.