Curtains! (almost)

People, I have a confession to make. We have lived in this house for 8 YEARS and I've never had curtains in my living room. Never. Ever.
I've never really been much for window dressings. I don't get fancy, I don't spend a lot of money. And for some reason I'm really intimidated by them. Silly huh?
So my goal for the last 8 years few months has been to finally make a decision on what I'm going to do with my big front window. It's a bay window, but not a cool seat type of bay window as it's 3 ft from the floor. The total dimensions, including the trim around it is 6 ft wide by 4 ft 2 in tall.
I know what you're thinking. Just make two long panels on each side of the window to kind of frame it. Yep, I've thought of that, and that's what I'm trying to go for. I even bought a curtain rod 3 YEARS AGO which you can see in the picture. It's been on the wall, taunting inspiring me for that long. But, (and it's a big but) there are heat vents against the wall directly below where those nice panel curtains would hang. Because they have to go to the floor. They can't be the same length as the window. They just can't. I'd feel like I was living in a Super 8 hotel. Not even a Holiday Inn Express, a Super 8. And even I don't sink that low. (Plus there's a little thing called money missing from my life these days, so there's another obstacle. Just throwing that out there.)   *sigh

 
Well let me tell you, I was at Target doing some Christmas shopping (with that money I don't have) and came across these shower curtains ON SALE.  And there were a crapload of them. In my color none the less!  I heard the angels sing, and then they started hacking and coughing like they were lifetime smokers because I realized that these shower curtains won't be long enough to reach the floor. But then they cleared the phlem and started singing again, because I realized I can just add a panel to get some more length! YAY!

But, (and it's a big but again) I can't for the life of me figure out where exactly on the curtain I should add the panel, AND (the most important part) which color I should use for the "extender piece".  *sigh    My living room colors are tan, white, red, and dark chocolate brown. Walls are tan, trim (except for said window) is white, hardwood floors are the ugliest scratched up Golden Oak color, along with the bay window trim, but accent shelves and such are dark brown.
HELP ME PEOPLE. What should I do? Do I use dark brown for the "extender piece"? White? God knows I don't want to try and match this red, you know how that can go.  AND, do I insert the "extender piece" at the bottom? Somewhere toward the top, but a little below, so there's red on top? Gawd, I just can't make this decision. This is worse than trying to decide what to use for the binding on a quilt. *sigh

(and yes, those are also white shower curtains in the picture, and they're for my next meltdown project.)