Here is a write up on my experience of this exact subject... The Gates of Lodore vs the First Day of Kindergarten.
Please take into account though what lmyers said about your experience and the comfort levels of both you and your kids. I am a very experienced boater and my daughter is a very seasoned camper and boater, so our comfort level is different than many peoples. Having said that, the Gates of Lodore definitely pushed my comfort level a little bit, (just with bigger rapids that I didn't know.) But for us the experience was beautiful and well worth it!
Also, just to throw it out there... there are a ton of Awesome multi day trips that have less intense whitewater. There has been a recent thread about it here
... Also, a great resource for family boating is the FB group River Kids,
and there have been some recent family multi day discussions happening on there.