It's harder to sell one with a rear galley as most owners don't want the crew going for coffee when they're trying to sleep. Have heard stories of a pink and fluffy interior on one which might be great for you but will a prospective buyer want it? Probably not. A 4 zone cabin configuration is great if you're not going far on your flights but if someone wants to take advantage of a 14 hour range, the extra pilot you need will be having dinner with you instead of hiding in the crew compartment at the front.
There is a G650 that's been on the market for nearly 2 years now and there's a fair old 2nd hand market out there so don't expect a quick sale especially if you ignore the above.