We'll do Trails End for breakfast when we're spending the day at MK. We take the boat from there over to Ft Wilderness and the Trails End is about 200 yards straight up the trail from the boat dock.
I think how busy depends on the time of year and probably which day, but we've never really had a problem (that includes in the past when we stayed at the campground in the cabins), as long as a 10-15 minute wait doesn't bother you. If you know when you're going to go, just make an ADR. You should probably allow yourself 1/2 hour from MK to Ft Wilderness.