Salvador, Bahia, Brazil
Doubt going from Paris to Cambridge: I like road trips and am wondering whether the bus ride would ofer me a nice view and experience. What is my better option, train or bus? (if the bus is just a waste of time, I appreciate your sincerity).
If the choice is between bus and train, I would recommend the train. The view from the train is at least as good as from a bus on a motorway, if not better. The Eurostar is also much quicker in crossing the channel than the ferry.
Finally, if you love road trips, why not look at a hire car option from Paris to Calais, then pick another one up on the UK side. Choose your route to include interesting and scenic options, with stops in little towns for refreshments. Much slower, but loads more fun.
The bus is going to take a lot longer, it depends on your time. I like the Eurostar train to London, then an easy train to Cambridge (England). I would go this route, I reckon you could do it in 4 hours or so, spend longer in Cambridge.
I've taken the iDBUS a couple times (both Paris-London and Milan-Paris) and would recommend the train, especially if you're older! My early 20s-body could take it, but these days all that time on the bus hurts my back. Plus you start to get bored and then take a nap, which means you miss the view anyway! Unless you're really trying to save money, I'd recommend the train.
I also wrote about my bus experience here, the night bus Paris-London route: http://expatedna.com/2012/08/30/night-rider-traveling-from-london-to-paris-by-bus/
I am the fourth one to agree with Michael and others. I would just like to add that after reaching London from Paris, driving in and out of London may not always be a very pleasant experience. But, you can consider staying somewhere on the outskirts of London and renting a car there onward.
Also, there are bus tours to Cambridge starting in London.
I second (third) the train..it's relaxing- well after you actually get on the train, you can sit, read a book, look out the window, people watch, take a quick nap..and it's quicker than driving! Plus it's probably less expensive...have fun whatever you decide!