I'm currently planning my first ALR this summer, but on a Two Together railcard to make 1st class affordable. It will unfortunately only be valid after 10am (my friend might be eligible for a disabled railcard; if so I can be a companion and this would remove the 10am restriction but as both of us live near London it's after 9:30am anyway).
We've both been over a decent chunk of Scotland so we can stay at home most nights as distances aren't so far. And we've both done London to Ediburgh a few too many times and my friend isn't a great fan of 390s. The plan is to tick off a few 1st class menus and interesting InterCity routes. Note some days were drafted before I realised we'd have a 10am restriction so might not be possible.
Day 0: Sleeper to Penzance
Day 1: GWR from Hereford. Penzance-Taunton 1st IET, Taunton-Newport-Hereford GWR & TfW, Hereford to Paddington 1st IET
Day 2: Everos and 810s. Euston to Chester 1st Evero, Chester-Holyhead TfW, Holyhead to Crewe 1st Evero, Crewe to Derby/Nottingham depending on what Class 810 diagrams are running and get that back to London
Day 3: Clockwise rotation to Scotland. Euston to Glasgow 1st Pendo, Glasgow Central/QS to Edinburgh, Edinburgh to Kings Cross 1st IET
Day 4: My friend loves Class 91s so we were going to try and spend of much time on one as possible... With the 10am restriction the best way is to drive to Grantham, get on the 1016 to Leeds then stay on the same set (Grantham-Leeds-Kings Cross-Newcastle-Kings Cross-Grantham) all day. The Newcastle-Kings Cross passes Grantham at 2020 or stay on and get off northbound at 0033. Might regret this one a bit!!
Day 5: GC 1st Class & Whitby branch. King's Cross-Eaglescliffe 1333 GC 1st, Northern Eaglescliffle-Middlesbrough-Whitby-Middlesbrough-Newcastle, LNER Newcastle to London.
Day 6: GWR Summer Saturdays to Pembrooke Dock from Paddington. Then back on the IET to Newport, try out TfW 1st Class up to Crewe (cheaper than Manchester) and stay in out only hotel
Day 7: Get up to Manchester than TPE West Coast Kitchen 1st class up to Edinburgh. Edinburgh to York on LNER (or TPE?) then over to Sheffield and catch a EMR diversion via Melton Mowbray.
Unrelated to planning my ALR, but on my website I have the EAS National Maps in a more easily accessible format than Network Rail's website with PDFs. While these aren't definitive (enigneering work may be cancelled or added after the maps are published, and some aren't included) it gives a decent overview of where engineering work is taking place across the country.
vaildata.uk