tarwheel has the right idea. If you're planning a long weekend ride, take extra care to make the commute the day before (or more, depending on how quick you recover) easier. And try to get enough sleep.
I started a similar situation a month ago - daily commute increased from 5 mi (8 km) to about 12 miles (20 km) each way. Once I got past jokes about the things a dedicated rider will do just to increase their mileage, yeah, it takes more out of you. How much depends on the base you're starting from, how quickly you recover, and how hard you're going on the commute. What works for me is I limit the "hard" commute days to 2/week (I treat them as if they were intervals training rides - typical programs for average joes limit hard/interval days to 2/week) and really try to take it easy on the off days. If you feel like you need a day off, you do - take it, or really ride easy that day if you have to ride. As your body adapts to the increased load, you may find you do not need as many super-easy days or days off as you did starting out.
I'm a data nut, which my wife sometimes thinks is obssessive-compulsive (she married an engineer, it's a feature, not a bug), so I see how hard or easy the commutes are and correlate it with how I feel the next day. And that traffic lights can have as much an impact on my door-to-door time as how hard I ride.
I've found that gear that was fine for a short ride may be inadequate when you are on the bike for a couple of hours day after day. I am really appreciating my quality bib shorts over the cheaper ones I was using for commuting, and watching for sales to grab a few more. I've tweaked saddle height and position and cleats a few times. I'm also paring down the amount of junk I carry back and forth and appreciating panniers over a backapck. I'm happy to discover that my old commute was exactly long enough to hit my maximum chill point before I started to warm up. We've had sufficient cold (for this area) days to figure out I don't need as much gear as I used to.