Same problem here, large hands.
I have a G9X and while the length is frustrating, the width is kinda okay. Mind you, things change depending on which "grip" you use. And yes, they made two separate sort of outer casings for the mouse you can swap depending on your need. Then there was a third (the "ID grip") but it needs to be purchased separately. It's supposedly the best for large hands. Well, I have it and it's certainly not bad for websurfing, Windows, Crusader Kings II, this type of things. Not decided about Starcraft 2 with it, might be too bulky. One good thing about it is that it comes with an additional large slider ("foot", hopefully teflon).
Counter-intuitively, a small mouse may also be good for big hands, depending on your grip. If it's not narrow or high, then you can simply toss it around the pad with your fingers alone, which I think helps ease the load on your fingers and generally your palms. While a person with smaller hands would need to wrap his palm around the thing, you could get away with using just your fingers for the purpose. I tried this and my carpals loved it but the mice generally were too narrow.
If you're feeling creative, you can do something like get an office mouse (there are millions, they're cheap, the staff will probably allow you to test them if you promise to buy one or two), then do things like sticking teflon or other custom sliders under them (or whole darn plate of teflon cut to size, why not). Amazing things can be done with large hands and long fingers.
Worth looking at might be Azurues and Saphira, both from TT e-sports. Azurues goes up to 2000 dpi (IIRC) and resembles an old-school mouse from the 90-ies. Saphira is similar but not as old-school and goes to 3500 dpi or so. Both optical, so you generally want a cloth pad unless you actually prefer hard pads for optical mice. I don't really.
Also, a lovely, lovely mouse I have here is the A4-tech X-478K. It has the same sensor as Logitech's 518. Okay, perhaps not so fancifully handled, customised, put to use, whatever, but the same sensor anyway. The form-factor is a bit of a rip-off from the DeathAdder but it is still noticeably different in its look, it's not a fake DA (always makes me think of "District Attorney", lol). It probably costs one third of the price of Razer or any other leading brand product and I'm pretty darn sure it offers more than 33% of the value! Mine came with spare sliders. It has adjustable weights, they didn't forget about them. The mouse must have been really successful because there's a new V-track version right now (thinner beam than laser for supposedly even better traction), similarly cheap and otherwise unchanged. Build quality is great (I mean it), it is rubberised just enough but not to excess, the place under the thumb has a grid to prevent your thumb from getting stiff on the mouse. If you rotate the mouse counter-clockwise a bit instead of using the most intuitive way of holding it, then it gets even better (especially with large hands, I guess). For the record, it is a big mouse, one of the biggest. If it worked for you, I'd stop looking further. For the record, I gave mine another layer of sliders on top of the existing ones to make it glide with less effort. Wasn't a bad idea.
EDIT: Sorry, Azurues goes up only to 1600 dpi but since other optical mouse tend to be interpolated at high res, pulling the speed up in Windows with this one would probably have the same effect. Dimensions aren't bad: 126.5mm (length) x 67.2mm (width) x 38.5mm (height).
http://www.ttesports.com/products/product.aspx?g=spec&s=14
