Oxford -> Christchurch is about 90 miles and goes through the New Forest, which could be fun. But it would be a tough route for the inexperienced cyclist. ...
The trouble with that, is that it's a bit against the ethos of the FNRttC, which seems to be about getting people to do these rides who have never done such a thing before. Several of the comments
at another place say things like
"...It was my first CTC ride, first night ride and first trip to Southend..." and
"...my first, but probably not last FNRttc. A gentle introduction with excellent weather...".
Whilst some of the rides can be longer, and hence slightly faster than others, I don't think we want to drift into the realms of "tough for the inexperienced". If people want to do more challenging rides, it's probably best if that is left to other mechanisms, and the FNRttC is kept as a relatively easy ride, achievable by most people who've done some cycling, but not gone on longer jaunts before.
If nothing else, the risk with a significantly harder ride, is that the TECs will end up being stuck with a greater number of progressively more exhausted people, and the whole ride will end up falling behind schedule. I suspect one of the problems with being at the back all the time, is that you never get a chance to catch you breath back and recover. Luckily, even though I've done little distance cycling for quite a few years, the 20+ commuting miles I do a day means that I've never had to suffer at the rear of the FNRttCs, but I feel for those who haven't yet achieved enough fitness to try and stay up nearer the front.
Having said all that, I don't think there is too much of an issue with the occasional ride which isn't actually to the coast, but I think the level of difficulty has to be moderated.