Hello all!
For those also looking for easy public transport walks, doing these hills from Crianlarich is a good option. This was the first time I have hiked solo in Scotland, having only started solo hiking in the last year or so. The weather was pretty bad, and sometimes low visibility, so it was a good test for navigation and keeping up moral. The hardest nav part was probably the forestry for me, as I didn't know Crianlarich village and there are so many paths that I was worried I wasn't on the one I thought I was on... if that makes sense! But whilst I doubted myself momentarily and backtracked for a few mins, I found some good points to work out my location from and was on track after all, so it was a good learning experience. Anyway, here are some notes about the route:

Exiting the train station, walk down the road towards the SYHA, and go down to the car park on the right sign posted 'mountain view'. From here, go over the little bridge and pick up the 'tourist' track until you come to the signpost for the forest. Follow this, picking up the forestry road for a while. The road splits twice, take the left the second time and carry on uphill, with the grey heights on your right. After a while there is a sneaky cairn on cutting up hill, following this cuts off a corner so you recross the road and carry on off-road up hill through some very, very boggy trees... I would gladly hear any recommendations of alternatives to this route, as it is pretty unpleasant!! I didn't pick a dry day which didn't help Once out of the bog, head up towards the ridge, and once there it is easy to follow the ridge along to the Grey Heights, and from there Cruach Ardrain. Or in low visibility the ground is wide and easy walking, slightly wet in places but mostly no problem.

You can pick which munro you do first, it is not necessary to summit Cruach Ardrain first, although you do a large amount of the ascent anyway. I went up Cruach Ardrain first, and if going this way, make sure to bear more left/ east for the way up to the summit. I think there is a turn off in the path but I must have missed it, so chose to cross up hill before it got too steep. Very little visibility on the summit! I retraced back south-west, found a path again where there was an obvious cairn and path divide heading towards Beinn Tulaichean. Lovely stroll along the ridge and easy summit, then returned back along, picked up the lower path to avoid Cruach Ardrain again (although it does feel like you do most of the re-ascent...) And headed back the way I came. Finally got a bit clearer weather! Although the return descent of the bog through the trees was probably even more unpleasant than the first time, and I had very very wet feet by the time I returned to Crianlarich. Had a well deserved cuppa in the pub before getting the 19:30 train back to Edinburgh (via Glasgow). All in all a very happy, if soggy, day out.