Here's a modification, that really transforms the look of any bike. A new stretched tank from an aftermarket supplier, say Fat Katz or Independent, will run about $1500 and up. One problem you might find though is, it might not fit upto your seat well. Ultimately, the solution for that is a custom made tank. The best part about this is, it will fit your seat like a glove, and is much cheaper ! 
I'll be using a 2005 Dyna Wide Glide. It's getting a beautiful Danny Gray seat. So I made sure to carefully tape  and wrap the new seat, so as not to damage it, with any sharp metal edges,when fitting the tank extensions.
Here's a look at the tank extension kit, these run about $150, and provide the basic shape, that would take a few hours and a host of metal working machines to make. These have the sexy shape that  makes the difference !
I started by gutting the tank, so nothing inside is damaged when welding. It also helps dry the tank out, so we don't have any explosions, when welding. So I start by laying up the stretches on the tank, just to see how it going to look and how it will fit. Once I get them where I want them, I tape them down and make some reference marks.
I then remove them and clean off the paint in the areas that I need to be welding. Then reinstall the stretches, line up on my reference points and tack weld each piece in place. Then trial fit it to the bike again, just to make sure that they are exactly where I want them.
There's lots of little pieces to be welded also, some that need to be made, that didn't come with the kit. So once I've tack welded the whole project together, and checked fit a half a dozen times. I'm ready to weld the whole project together for good. Then, all the welds get ground down, and readied for bodywork. I start with a good coat of Duraglass, to seal up all my welds, and create a good foundation for the Plastic to follow.
Some shots of the finished bodywork, ready for primer and one last check for fit, without the protective covering on the seat.
Here's the finished product in primer ! It fits great and creates a very flowing line, through the bike, that will only accenuate the paint .
Here it is ! Candy Cobalt Blue with triple ghost flames. The tank now flows right into the seat and frames the motor, for a very eye appealing look. The stretch modification costs  $600, including parts and if you ever tried this one at home, it's money well spent !