Woah, this thread got kinda popular today, huh? I just got home from work, ha ha.
The problem with the right one is white. It might work better with a darker color replacing it. This would require the Luigi sprite being removed or maybe making look like a gold Luigi.
Yeah, you're right about the white being the issue. I had a thought, though... There's another part to the Year of Luigi logo with a "sprite":

It can even be represented by only one or two colors, too, and they're colors that don't look too shabby together: the original SMB question block colors. Nintendo already did this in their own SMB 25th anniversary romhack:

So I could just change the "25" to a "30" and either use orange(brown?)-and-yellow or just white-on-black! This frees up the background palette a bit so I can at least ditch the white. I'm thinking I'll also flatten the black bar that it's in by a couple pixels so that the checkerboard pattern can peek out from behind it and remove a little of that cluttered feeling. I still want it to be a big "pill" shape so I'm not going to do something like GHANMI suggested, but it will look better.
Regardless of this, I think the year of Luigi text makes the screen far too cluttered the way it is.
I would also point out that none of the year of Luigi products explicitly say year of Luigi in game anywhere. Plus Dr. Luigi itself is already associated with it without the text telling you so.
Aaaaactually, I hate to break it to you but:

Still, I think I've come up with a solution to all this anyway. I'll just simply include multiple versions of the patch so people can pick what they want. It's not like this is an official thing going to retail so I don't have to pick one. Patches aren't that big on their own anyway.
I'm probably going to have four versions:
Dr. Luigi Lite
The hack as it was originally going to be, but with the newer logo lettering. All palettes are the same, the only changes are to the logos and Mario. This is for those who want the "how Nintendo would do it" feel, since this falls more in line with Luigi Bros. It's also the only one that'll have a properly centered title logo; tile attribute palettes don't let me do this for the green/grey 'asymmetrical pill' design. The other ones
are centered if you consider the trademark icon, but the original Dr. Mario screen didn't consider the TM part of the logo for centering so
technically this is "more centered".
Dr. Luigi Standard
New palettes, new viruses, and secret new ending animations! You'll actually have a reason to play this now! (Unless you cheat and go look at it in a tile editor, but that's no fun.) I consider this the "how Nintendo would do it if they felt like putting in some effort" edition.
Dr. Luigi: Year of Luigi Edition
New palettes, new viruses, the new endings, and the classy Year of Luigi title. Since I'm going to change it to the "30th block" I'll be able to revert the background palette to the better blue one. Still including this and Standard as separates to satisfy everyone (and because it's a romhack and I can do whatever I want).
Dr. Luigi: Green Cap Edition

I AM A WIZARD and I have used my powerful magic to grant Luigi his hat, as he has in the Wii U version. Unfortunately this breaks his victory/loss animations and I can't fix those, so this is a separate extra edition for those who want it. Just an idea I had that I didn't want to go to waste.
So yeah, that's how I'll do it. Four IPS patches all with the ultimate goal of simply giving Luigi his rightful place in another NES classic. I think this solution is good.
Make a decision, the year of Luigi is almost over.
Actually! Nintendo said The Year of Luigi will extend into 2014. And this makes sense, as it was only declared in mid-February, so it should last at least that much longer. I'm sad that the Luigi Nendoroid won't be released until June so that'll miss the festivities entirely, but at least they're making it!
EDIT:I didn't want to make this post any lengthier but check this out:

I'm very happy with this, personally. Less cluttered, more classy, better colorscheme. It won't replace "standard", but it will replace the orangey old one (unless someone really, really wants that).
And here, have a new video. I actually played in this one, showing off the game over animations:
http://www.youtube.com/watch?v=D3CHXLjBYik