The plan for today is for one set of walkers to go for a nice leisurely walk along the shore of Loch Lomond, and for another set of walkers to come with me up Ben Lomond. We won't go at warp speed, but we will need to get up and down in about 6 hours in order to meet up with our pals again in the pub.
The Ptarmigan Ridge is a more interesting way to climb Ben Lomond; it's a little steeper in places than the tourist path which we'll be taking back down to the car park, but there's nothing particularly scary about it.
The plan is for both walks to start about 09:15, and to finish a bit after 3. Then we can meet up in the pub and talk about the great walks we've had.
(Note that while I'm claiming that toilets are available, the LLTNP are pretty terrible at providing facilities so it might be shut or under repair or sold off for flats by the time we get there)