The Geneva-Le Puy section takes about a month of walking at my pace (15-18km, rest day once a week). So making the halfway point at Le Grand-Lemps worked as well as any. The other possible dividing point is Les Abrets, which also has a train station.
This section has some significant differences from the route after Le Puy. It is much more populated; so the towns are larger, they have more services, and they come along more frequently. Lodging choices are relatively abundant, and also more expensive (while walking solo I was averaging €60 a day; sharing lodging in the group averaged €40). This is an area favored by tourists so they compete for the lodging.
July, with its quite hot weather and its competing tourists, is not the right time to walk this section (nevertheless many do). It sometimes offers splendid views, which are rightly earned. The lower elevations are easier walking but not as visually interesting. The river dominates the geography, and offers boating and camping.
Most walkers encountered this month were Swiss. We found two Germans, one British, and one Austrian. According to one host, in the spring he gets the through-walkers heading to Santiago all in one go, in the summer he gets working people who walk 1-2 weeks on their holidays, and in the fall he gets retirees who are also walking fairly short stages.
Wifi was available every night save one; cell service was generally available. Groceries were less abundant and rather sporadic, so one needs to plan carefully, especially if camping and self-catering. (One Swiss family with small children at one of the campgrounds had been hungry, since there were several days without supplies early on.) Breakfast was typically generous in the French fashion: plentiful bread, butter, jam, and coffee or tea. Often cheese as well. Lunch was sometimes available at a restaurant if the day is timed properly. Dinner generally included an appetizer, plentiful main, cheese course followed by dessert – all featuring produce from the garden.
Transportation connection information in the Amis’ “yellow guide” is somewhat misleading, as they indicate train connections when there aren’t actually any. Check the SNCF smartphone app for actual train information. Buses are also notable by their absence and taxis are practically non-existent. So you and your pack are going to walk. This minimal transport infrastructure is a considerable difference from the situation in Switzerland.
Lodging hosts are friendly and helpful with recommendations, and will call ahead to organize the next night if asked. Calling for reservations is the norm; very few of these have email or websites. The Amis guide has all the lodging contact info.
On this section, I did not take advantage of any of the Amis private home accommodation; the one or two towns I checked, the homes were located in the suburbs and required an additional 2-3 km walk.
The campground facilities for non-tenting pilgrims should definitely not be overlooked. These can be a lifesaver when more standard accommodations are full, and a budget saver as well.
Drinking water was generally not available between towns; I have indicated every water point I passed on this route. Be prepared to bring enough water for your day. I often used my auxiliary water bottle as well as the water bladder when the day was hot.
The second half of the route crosses the Rhone valley before ascending the central massif that is the old volcanic heart in the middle of France. Just based on town distance my estimate was 13 walking days; however after looking at the elevation profiles – some days have a 1200m climb – I think 15 walking days is probably more accurate.
Perhaps next year, but surely not in July!