c) We'll be in NYC the week before we go to Chicago, and haven't yet planned on how we're going to get from NYC to Chicago we're currently considering driving, is that going to be wise? (weather?)
No. It would be miserable and dangerous.
First of all, you never ever ever want to drive anywhere in New York City or in about a 100 mile radius of it. The congestion will drive you nuts, as you crawl at 10 mph for 50 miles. In NYC you always take the subway, walk, take a taxi, take a train, or take a bus (in that order of preference).
Driving on the expressways in Chicago also sucks; everyone tailgates and it's quite dangerous. (The "surface roads" in Chicago are better.)
Second, NYC-Chicago is 789 miles on the shortest (and least interesting) road route, longer on any of the more interesting routes. Doing it in one day is a nightmare. It's longer than Sydney-Melbourne and comparable to Sydney-Adelaide. But with a lot more traffic than either. Sound like a fun drive? I don't think so.
Third, yes, the weather may be bad. We occasionally still get snow in the Great Lakes region in April, and if we don't, we may get torrential rain.
I've driven most of it (never all the way, I live 5 hours northwest of NYC) but I always stopped overnight at least once, and even then it was still a bloody slog. It's only fun to drive it if you plan to stop several times to sightsee, making it a three day (or more) trip.
Flying from NY to Chicago also sucks; all of the NY airports are an hour away from downtown, and so is the main Chicago airport.
Take the train.
Is there an interesting train routing you'd recommend? We're not super pressed for time, so we can explore interesting options. No problems flying either, but just feel like something more interesting this trip if possible!
There are at least two interesting train routings (and more less-interesting routings!)
The Cardinal from NY to Chicago isn't a very practical train due to the three-day-a-week schedule and very long running time, but it is a very interesting route to take in terms of scenery, giving you a slice of Virginia, a lot of West Virginia, and the Ohio River Valley.
If the Cardinal works for your schedule, go for it!
If the Cardinal doesn't work for your schedule, the Lake Shore Limited from NY to Chicago is also an interesting route, and it runs daily on a reasonable-speed schedule -- leave in the afternoon, arrive in Chicago the next morning.
I can *strongly* recommend the LSL from NY to Chicago.
The Lake Shore Limited runs through my home turf, upstate NY, which will look like nothing you have ever seen in Australia. (Though tourism season here is fall, when the leaves change colors.) The LSL also runs through Ohio and Indiana -- you'll see a grand view of the industrial side of Chicago in the morning approaching Chicago.
The only downside is that prices for rooms on the LSL can run high. They will probably cost more than the rooms from Chicago to Emeryville! (This is because they're more popular!)
Prices for rooms on the Cardinal can also run high, but for a different reason: the Cardinal has very few rooms, since it runs with only one sleeper car. (The LSL has two from NY to Chicago and another from Boston to Chicago.)
Since your schedule is flexible, you may want to look at Amsnag to find a "cheap" day.
http://biketrain.net/amsnag/amSnag.php
There's three other ways I know to get from NY to Chicago by train but I don't recommend them unless you want to stop over at another city.
Want to see DC? Take the Acela (or NE Regional) from NY to DC. Then take either the Capitol Limited or the Cardinal from DC to Chicago. (The Capitol Limited scenery from DC to Pittsburgh isn't that different from the scenery on the Cardinal and you get less of it, but it is quicker.) You can do this without staying overnight in DC, though you don't get that many hours.
Want to see Boston? Take the Acela or NE Regional to Boston, spend a day there, and then take the Lake Shore Limited from Boston to Chicago. (You can actually do this without staying the night, but you get only a couple of hours in Boston.)
Want to see Pittsburgh (I can't imagine why)? You can take the Pennsylvanian from NY through Philadelphia to Pittsburgh, and take the Capitol Limited to Chicago. The connection is at 1 AM, so this is only sensible if you want a day in Pittsburgh, which I don't particularly recommend.
I think that's all the sane options, though I could come up with some more if you wanted to see weird little places like Springfield, MA or New Haven, CT -- there are definitely a lot more intercity train options from the East Coast to Chicago than you get with trains out west of Chicago, or in Australia.
d) We're spending a week or so in San Francisco, before heading to LA to go home. We're currently considering taking the Coast Starlight from SF to LAX is this a worthwhile experience? Any thoughts or suggestions are welcome!
Yes. I enjoyed that particular route quite a lot. I think it's probably not worth spending money for a room on that route as it's during the day (...though I did spend the money on the room because my fiancee disagreed with me).
A few things you should know:
(1) There's a "Flyaway Bus" service direct from LA Union Station to LA Airport which runs very frequently 24 hours a day.
(2) Union Station in LA is worth seeing in and of itself. Spend some time checking it out.
(3) It may be worth spending a day seeing some stuff in LA. Contrary to its "car city" reputation, LA has a pretty good subway and local rail system and you can get to many of the tourist attractions with it. (LA also has a pretty darn good bus system -- don't be afraid to use the buses on Wilshire to see more tourist attractions.)
(4) You probably know this, but the Coast Starlight doesn't actually stop in San Francisco proper (due to the Bay), it stops in Emeryville. Amtrak provides a connecting bus to San Francisco with luggage service.