Duluth Area residents: bike trail question

Hey north shore friends,

I will be up there in two weeks for the Burrito Union tri at Pattison State Park on Sept. 12th.  On the 13th, I wanted to visit a few sites like Gooseberry Falls, Split Rock Lighthouse, etc, and was looking at the Gitchi-Gami State Trail (http://www.ggta.org/index.php) for a bike ride.  

Basically, I am looking for:

1.  Easy flat ride
2.  No more than 30 miles round trip, 20 better.
3.  Good sights
4.  Parking access

I am trying to make sense of the descriptions of trail access, access to the lighthouse, etc. and it's confusing to me, not knowing the area.  I also am not sure if there are parts that are connected now, that might not be apparent on the web site which appears to be out of date.

Or, any suggestions of biking in another prettier area that's not too far from Duluth?

Thanks!