OP - DisneyObsessed - We stayed at GCV at the end of February / beginning of March - 2BR for three nights / four days. We lucked out and received a "theme park view" - the pictures posted here are pretty accurate.
DLR is NOT really like WDW in that the theme parks are so close to one another. We had a "four day parkhopper" DLR pass that had to be used by the end of the stay. We have a 5YO + a 7YO. Had we not had the 4 day pass, we would probably not have gone to the parks on the 4th day. We had a full afternoon at the Grand Californian's pools also in the stay (it was REALLY cold & rainy while we were there, so the heated pools / hot tubs were nice).
This all to get at your original question - is GCV for six nights worth ten nights at your WDW resort. I would suggest a happy median - say four nights at GCV (5 days), and save the remaining points for your next WDW
DVC getaway. Unless you're planning on exploring other SoCal areas, a rental car (we found) wasn't necessary. There is a (you-pay-for) shuttle bus from both LAX and SNA (Orange County) airports to DLR. I was skeptical about it - but it was the best. Go on-line and get the discount coupons, and let the bus driver worry about SoCal traffic. I had a soda and talked with the children about which rides we wanted to ride first on the bus ride. Use the Von's (Safeway) free grocery store delivery (on-line coupon) and save a few dollars eating in your DVC room (you still have to pay for the groceries - but like at WDW, GCV has coolers/freezers to keep your cold stuff cold).
Use Hydroguy's tips for touring DLR and you can see and ride all of the attractions you want to see in your 3, 4, or 5 days at DLR.
GCV is great - we want to go back fairly soon. But I think you could strike a compromise to save your vacation points for trips to both DLR and WDW.