we did the portion of the trip you would be doing when you hit california (we got on in davis ca and rode to olympia wa).
DEFINATLY do not rely on amtrak's schedual-based on our experience, and what we were told by train and station staff on that leg of route, it rarely runs less than 6 hours behind schedule (in our case it was over 12 hour delays). the issue is that amtrak does not have right of way on the rail lines, so the freight trains call the shots so if it's a busy freight period, you have much longer delays), and when you start getting into the northern california and oregon portions of your trip, the freight delays are much more substantial.
let your hotel know you may be delayed (we almost lost our room due to excessivly late arrival, and the car rental place being closed so we had to find alternate transportation to hotel/back to car rental place the next day).
the route you would take entails a bus ride for the final leg of your trip (seattle to vancouver)-i don't know how amtrak handles these, and what happens if your train is delayed after the schedualed departure of your bus. you may want to check on this (on another vacation, before we moved to washington, we did an alaska cruise out of vancouver but did a couple of days in seattle first. we looked into using the amtrak bus for the seattle to vancouver leg, but their schedual was pretty restrictive and limited in availability so i would be concerned as to how you would get from seattle to vancouver if you missed your schedualed bus and had to wait a significant time to catch another).
when we went, ds was 10, dd was 13. if we had not had game boys and one of those pre-loaded movie players amtrak rents in some stations we would have gone nuts. the kids got bored with the scenery pretty quickly. the "family car" (or game car) had nothing but old board games with missing pieces, and a few sets of cards. we had the larger

lmao:

) family sleeper car, which even with the beds folded up offered less space than a standard gas station bathroom stall (the standard sleepers were about the width of less than a double bed, the length of a single bed (when the beds are opened there is no floor space in those "rooms"). we all arrived exhausted.
dh and i would like to travel by train again someday but without the kids. i think one of the most stunning routes would be the one you get if you do an alaska cruise that is land/cruise.
if it were me in your shoes, i would consider doing the train from chicago to southern california, and then flying up to vancouver (avoiding the bus alltogether), then flying home. it will give your dh an overnight (at minimum

) taste of rail travel such that you can decide if a longer trip is in your foreseeable future.