Our household has never had a car so from birth I've been wheeled/toddled onto all the public transport options available from our wedge of inner London. The first journey I can remember was a day trip from King's Cross to Cambridge on a 317 c.1989. I was three, so hazy memories exist of NSE colours in the sun at Cambridge (and red station furniture - all the primary colours must have been quite stimulating to my junior eyes!), then of the 'upturned broom'-style pole mounted illuminated station signs getting back into KGX after dark. No idea why that image in particular stuck with me.
Many trips between Seven Sisters/Angel and Elephant & Castle via the Victoria & Northern lines in 1990-1 - I have much more vivid memories of these, and this was when the Northern was truly deserving of it's 'misery line' status, dingy lighting and crowded, all creaks and bangs from the 1959 stock as the train visibily swayed, dipped and rose along the City branch, grab poles swinging in unison as we went, wall-mounted tunnel cables oscillating wildly with great clarity through the single glazed windows. The exteriors of some of the units were a mess but apparently I was fascinated by the graffiti! Less so by the island arrangement at Angel where I was convinced nowhere on the platform was a safe distance from the edges where trains would seemingly belt it in from the tunnel mouths. Do the 1996 units tackle Clapham N/Common at a more sedate pace these days? It feels that way.
I don't think I went on a proper 'intercity' journey until 1997 - Euston to Glasgow Central headed by an 87 which conked out at Lancaster. Free Virgin Cola was doled out which got younger sibling and I buzzed up, probably to the annoyance of the other passengers as we charged up and down the aisles and played in the vestibules! Then out of Glasgow Central low level (via the grimmest station toilets I've ever seen) to Lanark (why we didn't change at Motherwell I don't know) on an SPT orange 303, past miles of abandoned industry and estates ready for demolition. Even having spent years in some of the most run down areas of London, the scale and extent of what I saw heading away from Glasgow on that trip always stuck with me. Pulling into Lanark felt like another world.