Wow! Thank you everyone for your replies and advise. The problem I have of power-sucking equipment seems to be two fold: First I have a couple of Williams Crown Edition locomotives, particularly a NYC Niagara) that are current monsters on their own. Second the Williams streamliner passenger cars both pull heavy and don't light up well.
I have two Williams Crown Edition sets with color-painted silhouettes that are the worst offenders. One pulls a little less heavily than the other, but both have dim bulbs and seem to hold back locomotives that already gobble up lots of current. Plus, I have had the truck spreading and derailment issues, requiring the pins to be smashed back down into place to pull the everything tight again. I think that this is a necessary evil...meaning that the trucks may be tight but now don't pull as easy. I have everything oiled and I cringe on the thought of doing it again as the track becomes an ice skating rink for at least 3 weeks and requires me to wipe it down over and over again along with the locomotives. The cars aren't squealing down the track, so I assume the oil isn't a problem.
I only have one Lionel set...but have never ever had an issues and some of the above responses indicate that Lionel cars may just be better...and that others have had derailment issues with the Williams cars. I think with what others are saying here, it appears that Lionel cars may be a better and more reliable setup...albeit at a higher price tag. There seems to be much positive feedback for MTH sets as well...and I may look into that. What I have against MTH as I know someone who has a bad truck for a passenger car and MTH just isn't making parts for them anymore or isn't standing by their product...so I am basically in the same boat as with my Crown Edition stuff if something goes wrong.
From what I gather here, again, it seems that Lionel cars have more reliable trucks and pull easier...one of the two factors causing my ZWs to cook after an hour of run time. The other is the cars' current consumption as well. Thank you Gunrunnerjohn for the info on LED lighting. I have seen it on other posts before and is helpful. Not to take too much away from this thread, but I think I will ween off the Crown Edition passengers sets I have and slowly replace with Lionel ones. They are brighter and pull easier. They don't have color picture painted windows and have easy to see black silhouettes against smoked glass/plastic. The clear windowed cars are EXTREMELY cool buy are probably off the table for now. If I could make the Williams cars roll easier and more reliably and retrofit with LED's affordably (not $35.00 per car as I saw on eBay for a setup that requires minimal tinkering to install), I would probably keep the Williams sets. Has anyone tried to light up cars like these with LED's and have no problems back lighting the colored paper silhouettes? How would I uplight the dome?
I will make a separate thread on LED lighting once I have all these passenger sets in order and have a good soldering gun. Heck, I've rebuild a house, so soldering some electrical connections and boards together is like doing that on a micro scale!