thank you for all the responses.

I have done 2 connections at SEA in the last year and had assumed that I'd be needing to take 2 trains which, yes, makes this all very tight and stressful.

It is all on one ticket (AA stock) so I am protected. it's in July. I had originally booked 6am YYC to SEA with the 1.30pm BA to London. either the BA flight or the later AS YYC SEA then got moved by 5 mins and for some reason I got auto-rebooked on the 11.40 YYC SEA which I was initially pleased about. I think then the BA flight got changed to 5 mins earlier so 65 mins became 60 mins (not that those 5 mins make much difference but I think something like a 5 mins extra might have triggered the auto-rebook).

I am sort of relaxed about potentially having to take the later flight - it would eat into a few hours of working the next day but 'outside of my control'. probably will be checking a bag in.

Don't particularly fancy asking to be moved back to the 6am YYC SEA as that's painfully early and means 6+ hours to spend at SEA (or yes, trip downtown but after a week's holiday in Canada, not sure that is really 'adding much'). My alternative is to asked to be routed via ORD (but gives me 6 hours there and a shorter night flight which means less sleep) or via DFW - which would give me a shorter (just under 4 hours) connection, 45 mins later departure (6.45am rather than 6am) and probably the new J product on AA's 789.

So wondering whether to chance the SEA connection with the knowledge that it's 50/50 I make the planned BA flight or a later one or later connection - or just move to the DFW option.