When I stay at the cabins at FW, I tend to drive everywhere but MK unless I plan to have any chocoholic beverages. It would only be about a 15-20 minute drive going via Bonnet Creek and Buena Vista Dr.
If you want to go via WDW transportation, then time of day would play a factor in the easiest way to get there. I would either be boat from FW to MK then bus to BC or bus from FW to DHS and boat/walk to BC. Each of these would likely take at least 45-60 minutes, but could take a bit longer if you have any longer waits.