Good endurance lines?

After having done only one Competive Ride, (15 mile novice) with my 12 yr old daughter, I've not been too experienced on what are the "good" endurance Arab lines everyone is speaking of. This was the first ride for my daughter and her 12 yr old Arab, Ranief, the first year they have been able to trail ride together. They did GREAT! Ranief's PRs were outstanding, especially since we did not do extensive conditioning and thought this to be a fun thing.... compared to the stress of doing even local county fair shows. Nina took a first place in a field of 15 open competitors. Her score would have even been higher except she had to wait for mom a bit. (Storm likes his groceries a little much, plus being black and a heavily muscled Morgan, slows his cool down time). We enjoyed it very much and plan on doing more in the future including a local ride in October, at the Pine Marten. Ranief's sire is a Ferzon grandson and his mother is a Naboor granddaughter. Would love some input on these lines.