The "Upper New" as the raft companies advertise it is from Stone Cliff to Cunard. It's about 7 miles long. Technically this is the Middle New, but as long as you know the put in and take out....
I have taken many families with the kids in inflatable kayak's (duckies) down that stretch at lower water. Most of it is flat. However, you will find that at this time of year (with water anywhere between 2 and 7 feet on the Fayette Station gauge) a couple of the rapids will become prett meaty class 3's. Rudy's Ripple can flip you, even in a raft, and at around 2 1/2 feet, Surprise is THE best hit on the river! I would say if you know how to swim and have a little boating experience you should definately check out this stretch! Stone Cliff is at the Glen Jean/Thurmond exit near the NPS office and historic Thurmond.
As for the Lower New from Cunard to Fayette Station, I wouldn't go there unless you are comfortable in big water class IV. People talk about class V out there, but I think you really have to make it that by running certain holes. If you aren't an experienced boater, you might find those holes....
It's an amazing stretch to see though and I've duckied it many times.
If you need more info, or want someone to take you down the Lower New, call Rob Dobson at WV Adventures. His number is (88
292-0880 and his shop is directly across the highway from that Glen Jean/Thurmond exit. If you're cool he'll hook you up, let you use his duckies and take you down the lower. If you're not cool he will heart punch you and take your wallet.