I've done RS (and Road Scholar) tours to Italy and France in both Spring and Fall.
I did Heart of Italy one May and Best of Europe (spends a week in Italy), Village Italy and Best of Italy in Sept/Oct.
I've done Rick's Paris and Heart of France in late Sept, plus Road Scholar trips to Brittany and Normandy in April/May, Provence in October and SW France in October.
Honestly I try not to do the very last tour of the season. Sometimes the guides are mentally "done" by then, sometimes some of the venues are closing down which would be more likely on Village Italy than on the Southern France tour. When we did Village Italy it was the last tour of the season and the last hotel had very few guests after the tour left (we stayed an extra night which I would not recommend). This was before Covid but I think they were closing for a seasonal break.
The gardens are better in April and I get what Martha said about daylight feeling short in October. Go to www.sunrisesunset.com to get a calendar of times for your dates. Be sure to check the box for Civil Twilight times.
Having said that I've got tours to France with Seymour Travels set for October 2024 and October 2025 just because that is when he is offering his limited dates.
I'd expect rain in both seasons. I would want a waterproof rain jacket for both tours but you probably have that already. Italy was hot for me in Oct 2022 but that might not bother you at all.
I completely hear what you are saying about feeling like you are running out of time! I'd probably edge to doing the April dates over the October dates if everything else is equal. Easter is April 20 in 2025.
FUN plans!