It's expensive, but Exeter ticks every box.

NH isn't really great for nightlife, so Exeter may not have what you're seeking in that regard, but it's only 20 min to Portsmouth and Hampton. 30 to ManchVegas. Hour to Boston (and there's a commuter train that stops in Exeter and goes there). Just over an hour to Portland (train goes there, too).

Exeter has a vibrant downtown (plenty of retail stores and no real chains), is 15 minutes from the ocean and offers easy access to I-95 via RT 101. It's got good schools, very little crime, several gyms of all types (including a ninja warrior gym opening soon), and has a hospital. Plenty of properties are on at least one acre - per your specs - but houses are expensive. Still, it's a great place to raise children if you can pull it off.

Good luck!