tNuvolari

So I'm in a new location now (TN) after many years in Los Angeles where there aren't very many hills in the city, or at least nearly none between my usual ride from Hollywood to the beach and now I'm having some pain with the hills here. I have a 10 speed drivetrain with a 12-25 cassette and my options in bigger gears are limited as it's Campagnolo. Anyway, my question is if I will notice a change to a 26 from the 25 or is that a lot of trouble and money for that difference?

Campy has a 13-26 or a 12-27 which I would rather have but they are not as popular so they're a bit harder to find these days. And wondering if I'll notice any gaps in between 12 & 27 where they've left out gears? Probably not as now when I shift with the 12-25, it seems like the middle gears are very close and not all are needed. Unless I'm tired, then sometimes that closeness is perfect I don't think I need anything bigger than 29 as I'm not talking about intense, long hills and my short cage will only allow up to 29

Just would like to hear what you guys think is my best course of action or if anyone has any suggestions about all of this. Even already I've noticed that the true key to all of this is to ride more hills and build up muscle and strength. But it's pretty difficult at this age (57), I admit, as there just isn't any reserve when I try to stand in the saddle and power up a hill; it is just painful and difficult!