Aaww, planning on a new tank

Well if you have the room and money, I'd always say the bigger the better. With cichlids and fish that live on the bottom, a bigger footprint is of advantage anyway, plus the additional height means more water, hence cleaner water with the same amount of fish, or just room for more fish (now who would've thought).
I don't think that a wider tank would pose a problem with watching the fish, guess you're gonna have tank lights anyway? I got a corner tank and no light really in the corner but it's still not dark there, and it kinda looks cool when the fish come out of the corner into the lit area.
As for additional fish, there are *plenty* of possibilities. One of course being other Oscars, so if you're planning on rescuing one or two somewhen, I wouldn't add too many tankmates from the beginning. Another thing to consider is if you want to breed the O's and raise the fry. Plecos have a tendency to make eggs disappear over night. If you want to raise fry, you may need a growout tank additionally. Breeding O's might get somewhat aggressive so any possible tankmates should have enough places to hide away. Besides plecos you could put in some non-cichlid tankmates like a few Silver Dollars and/or other cichlids, where you want to consider again they might breed themselves and possibly cause trouble. Like one convict would be fine most likely, a pair might be difficult. No experience with JD's, still there are plenty possible species anyway, like Severum, Firemouth or other Thorichtys species, those jade-eyed cichlids Penn got, Blue Acara, Nicaragua cichlid ... too many to name, basically mildly to medium aggressive medium sized cichlids or rather peaceful bigger ones. Always depends on the individual personality as well anyway.
So depending on the size and species you want, you could add quite a few single ones or just a pair of something when it comes to cichlids, best to post some ideas of yours. With two additional O's AND other cichlids, I'd go for the bigger tank since at least in breeding mood they will claim a territory and you need room for the rest. They might claim i.e. 4' of the tank length (no clue), no matter if 2' or 2.5' wide, but the bigger water volume is still a plus.