You can also take I-83 to 581, 581 up to 81 and 81 in. Regardless, you'll hit bottleneck in the mornings where 81, and 11 meet up.
The traffic lights on 11 aren't bad at 7 or 8 in the morning. I've done it now for two years. The only problem is the above-mentioned bottleneck. But if you leave early enough (like MEK does,) you won't have any problems, and 11 is kinduva fun cruise - LOTS of rubber necking from local residents.
On the way home in the afternoon, the 81-581 trip is great - virtually dead. Most traffic is heading the other way out of Harrisburg.
Jeff