Alrighty then. Let's think about this. So, if you do the math, turning around at this point (Lulu) would give a nice hike of just around 7.4 miles. That's normally enough to make a person feel like they did a little bit of walking. However, the sign says, from where I parked the car, that Poudre Pass, the head of the Colorado River, is 7.5 miles. So, that would be a 15 mile hike round trip. In addition, most of the hike to Lulu is very mild in nature. Sorta flattish. However, you gain some quick altitude in many places once you get past Lulu. The final thing is that there isn't any real "destination" before Poudre Pass other than what they call the "Little Yellowstone" canyon. So, if you want to head to Poudre Pass, you better be ready for just a bit of a hike.
One final note. The hike to Lulu is pretty safe (relatively speaking) for children. Even smaller children. There aren't any real cliffs to fall off of, you just need to keep the kids in sight at all times. The same cannot be said for the little Yellowstone area. There are some very steep (and long) drop offs right along the trail that could be construed as "not child friendly". If you take your children up to the little Yellowstone area, not only keep them in sight, but close at hand. At certain places, depending on the child, you maybe should keep their hand in your hand.
So, I thought about it for a few minutes and then, particularly since the day looked so nice, decided to go all the way.
You will come to a fork in the trail prior to crossing the Colorado River.