LV speedy 25 in both mono and damier. It's cheaper then anybag you've just mentioned, but those are the staple bag for LV i think... and it made from canvas, so in case you've gone to some rough and tough place, and need a throw away bag, this bad is the best.
All of my bags are sort of staple bags. My black balenciaga city is a staple bag in black and my speedy 30 is a staple bag in terms of classic luxury, timeless style. I consider these two bags to be my most "iconic" pieces that I could see myself loving and using throughout all stages of my life.
sounds to me like you have the black bag covered. my suggestion would to be to add some color, and nobody does color like Balenciaga. you could get green, red, or many other colorful choices. If you're not into bright colors, balenciaga has some amazing "neutral" colors.
I have a fantastic cement grey one, and a yummy chocolate colored one. The thing about bal bags is that they are extremely functional. they can be casual (on the shoulder, tassles flying), or a bit more dressy, (tassles tucked in, hand held). Whatever you choose, isn't the hunt fun? Good luck!