If its a remodel, run all your wires to LV boxes and you can put any plate you want on it afterwards, there isn't much to choose from I have the plain white ones in my house, on the ceiling from my surrounds, int the walls for the front 3... There is a thread around here {I don't know how to look them up} that I put a bunch of links to the stuff I used for my HT... For the terminal plates if you want something fancy you can buy
Amazon.com: Monoprice Banana Binding Post Two-Piece Inset Coupler Wall Plate for 1 Speaker: Electronics and then throw out the plastic surround and use one that matches your other outlet and switch covers
Satin Nickel Deco Step Style One Gang GFI/Decora Opening Wall Plate - Amazon.com {for example} then paint the white insert what ever color you want...
Also my brother used these
Amazon.com: 1-Gang Decora Light Switch Wall Cover Plate DecalSkin - Mystic Skull: Everything Else on all of his plugs, terminals, and switches in his HT, he picked all dark ones with pretty cool images on them. They will make custom ones too...
I wouldn't worry about sq, its just a terminal, but do it the way that looks good to you... With my first house I was crazy about which switch covers and which color hinges and knobs on the doors, now that we have built so many, Im like "white plastic and brass hinges and knobs" done.. My first house was all stainless hinges, and knobs, and grey switches and receptacles with stainless plates, and make sure the door bumpers all match.. that gets old, no one even notices that stuff...
One more point, if you are putting in "in wall speakers" look into just building in a recess for some bookshelfs with the terminals in the recess, this is much better than an in wall speaker, pick a bookshelf and build a finished recess, plastered and painted.. at least if the next potential buyer doesnt want built in speakers they will have a nice little shelf for their wedding pictures...