Randy from the Wyo area, welcome to our forum here! First off Lake Granby isn't up on the Mesa and if there are Cutties in there would be very hard to target. It is known for Lakers, Kokes, Big slimers and Browns. If you want info on Cutties on the actual Mesa maybe someone will toss out some helpful tips or else you can use the search function to look for more, a lot of good info in the archives.
There are a few Grandby Reservoir's up on the Mesa around the Battlement lakes, with a couple bigger than the rest (some get dried up). Beautiful area on the mesa. This particular area can become popular though as it is easily accessible by vehicle and nice for camping with ATV's.
I recommend Big Creek and Atkinson Reservoirs. Don't overlook the streams either.
Yeah Tony, if you are going to have 1 Grandby why not have a few more. I was fortunate enough to spend time on the Mesa while living in Junction for a few years, more time on dirt bikes and hunting than fishing though. Tons of locations to choose from.
A lot of people liked Bonita and the Cottonwoods too.
Every thing is open on the Grand Mesa due to a lack of snow. I don't know about the fishing at the Grandbys but I understand it takes about 3 hours to get there because the ATVs have beaten it to death. If u do go there the 4-5 10-11 complex of lakes would probably be the best. Other spots to look at that are more accessible are Cottonwood 5, Military Park and Cedar Mesa.