Post Covid, where the railway will need all the revenue it can get, shrugging and saying 'too difficult' may not be an option
Depends how expensive it's gong to be, considering how many passengers are going to be a premium each year - I don't know how much each 153 conversion will have cost ScotRail but how many additional Glasgow - Fort William fares do you have to flog to pay for it?
What economies of scale are there for building such bespoke stock versus the number of lines where you'd be running them?
Are you converting the limited number of 153s still around (which would be a lot more complicated/expensive than just converting them to bicycle storage) or are your building them as DMUs that can operate with a variety of other DMUs (since the different UK lines where such "scenic" tock operated aren't all operated by one type of DMU)?
Or are these going to be unpowered carriages that a DMU can haul (since we don't want our rich tourists to have to listen to underfloor engines)?
Would they have corridor connections to the other carriages on the train? Not that this will help if the rest of the train is a 170 of course. Are you expecting to have a dedicated member of staff in the panoramic carriages?
Will a single carriage be sufficient to cope with all of the different sizes of groups that would want to travel together (or alone)?
To take one line as an example (e.g. WHL), would the panoramic carriage be on one service/diagram a day or would you be wanting to have a panoramic carriage on each service?
Switzerland at least has more of a year round demand, whilst the demand for "panoramic" coaches will be less given that it gets dark in northern Scotland around half three in the afternoon during winter.
Commentary on the scenery sounds feasible but there's a difference between "commentary on an open top bus service, where you're only doing it once" and "commentary on what the dozen bus stops are between my house and the city centre on a modern Stagecoach/First vehicle" (which gets repetitive very quickly and a bit annoying - I know that enthusiasts on here like to complain about the frequency of announcements on trains) - is there an implication that these lines (or at least the First Class on these lines) is only going to be something that people would do once, rather than several times (at which they'd get annoyed by the repetition)?
Don't get me wrong, it sounds like a lot of fun - I grew up doing things like sitting in the rear carriage of 101s in East Lothian to look through the "driver" windows to see where we'd come from, occasionally getting a shock as an HST came past in the opposite direction and the whole DMU wobbled slightly in the draft - it'd be nice if a solution could be found (that doesn't involve spending millions of pounds on a very marginal increase in revenue on some remote routes - I think there'd be a lot of arguments from people seeing "urban" routes cut whilst funds are found for "vanity projects"
One thing that doesn't tend to be mentioned in these threads is that providing such daily services on routes like the Settle & Carlisle (one of the OP's examples) may make a number of rail tours uneconomic (it wouldn't remove all of their passengers, sure, but if people can travel over Ribblehead in some swanky panoramic carriages for the price of a regular First Class ticket then it's going to be harder to get them to pay for a rail tour)
I do agree with the idea that we could make some cheap improvements to attract "leisure" passengers. Nowadays, if you go into a mainstream pub (e.g. Wetherspoons) you'd expect them to hand out crayons/ colouring sheet for kids - it's expected - I liked the idea that Grand Central had where they have chess/drafts boards on the tables - an easy/ cheap way of providing some entertainment for the family - maybe there's a separate thread to be had about low budget ways of making train travel "nicer" for families (without "introduce compartments for solo travellers, replace all of the seats" etc etc)