Thanks for the replies.
The new job would be a for a different company, but essentially the same job I'm doing now, just PT. I don't hate my job or the company I work for, but really do get burned out at 40 hours per week and they (current employer) won't budge on my schedule. My access to benefits / 401K is a little unclear should I take the new job; although my understanding is that I can get health insurance, just with a higher employee contribution than a full-time worker. I need to ask about 401K, but it feels weird to ask about benefits before applying or before the job is even offered to me.
In terms of what I'd do with my extra non-working days - I'd like to be more engaged with hobbies (woodworking, gardening, cooking), spend more time with volunteer and church communities, and I would like to do some traveling, although I tend to travel more locally, so long weekends would actually be pretty sufficient for a lot of the trips I'd like to do. I do know that I would still accrue PTO, so could hoard PTO hours to do a longer trip as well.
I like druth's suggestion of using the spreadsheet to look at all of my options and compare. I'm thinking maybe I should apply for the PT position so that I can get clearer on the benefits (health insurance, 401k) and then I can decline or accept the offer should it match my goals.