Where to view the most Amtrak and freight action in Chicago?

Where in Chicago can i see the majority of the amtrak that leave/enter chicago union station and see freight also

any spots around the station where i can see both freight and amtrak

if its far..........can i take METRA there?

There's four spots on two different streets that cover all passenger trains in town:
1. Canal between Kinzie and Lake covers the Northwestern Station throat tracks and CUS-North throat tracks. (Hi, Builder, Metra MILW, Metra NCS, Metra UP)
2. Roosevelt between Canal and the south branch of the river covers CUS-South (most Amtrak, Metra BNSF, HCS, SWS)
3. Roosevelt between Clark and the south branch of the river covers LaSalle Street Station approach (Metra Rock Island line)
4. Just east of Michigan street, Roosevelt, Adams, or Van Buren cover the approach to Randolph (Millenium) electric terminal for Metra and South Shore trains.

Best to plot out your adventures with google maps using these four spots. When walking from 1 to 2, you can walk through Northwestern station, Boeing building (check the Boeing store), and CUS. Enter NW Station at the Lake overpass, exit the south doors - go back to the riverfront and walk south to the Boeing building. Continue south to the platform entrance for CUS-north, go down the stairs to the platform. Walk south to the waiting rooms, and exit to Canal. head for #2.

With all the mergers, I don't know how many freight transfers still ply the downtown trackage. Most of the old freight houses are gone. The best spot for some freight action depends on how much CN uses the old IC via the air line connections to Glenn yard & the western Iowa line. It may be a matter of time before most of this traffic is on the EJ&E. You may want to ask your question on Trains or another area that has a better freight rail coverage. The 2 heavy passenger/freight routs are further west on the BNSF racetrack + some SOO freight on the former MILW lines. You can try using Metra trains to check out the UP line west of Proviso.

I would say to go out on one of the commuter lines like BNSF Chicago Sub. UP west line in Elmhurst is good too. SOO would be seen from the Milwaukee North Line. The Milwaukee West Line might be ok to see IC&E.
The Rock could get you to Joliet. The former Santa Fe is the big show there, but UP or CN might be seen.
If you are not dependent on public transportation, Blue Island is good. The BRC Clearing is good too. This is near Midway Airport.