I lived in Charlotte, NC for a few years, and I'd recommend that area or Raleigh to anyone. Plenty to do, access to anything you're looking for, cost of living is relatively low. I grew up in Upstate, NY, moved to NC, then came back to the north for work, and to be closer to family (all in New England). Depending on where your families are, and where you'd really like to be geographically, I can't say enough good things about NC/SC.
Lots of outdoorsy things to do? YES. Plenty.
Quality state/national parks within an hours drive? Absolutely. You can be in Boone, NC or Asheville, NC and catch the blue ridge parkway in either place.
Charlotte and Raleigh are big cities. Fly anywhere direct from Charlotte with ease. Bonus is easy access to I-77/81/95.
Bike trails? YES! I'm a bike nerd (read: I have 9 bikes currently and love to build vintage 80's hardtail bikes), and Charlotte has an awesome set of trails, and you can be at Pisgah national forest to ride in a little over an hour. I actually miss having multiple bike trail options IN THE CITY like Charlotte has. I would often fit in a quick ride after work. If you're into racing, there is a weekly race circuit in Charlotte.
Affordable? A THOUSAND TIMES, YES. I still own a house there and rent it out actually. For scale, my MORTGAGE on the house in Charlotte is literally $1350 LESS than my RENT here in Boston. A BIG, newer house in a nice neighborhood can be had easily in a $200k budget. Even Cheaper if you cross over into SC.
Friendly people? Yup! After living there, then coming to the Northeast, its like day and night. I still have a ton of good friends in CLT.
Beaches? They are 3/4 hours away... Like you, I prefer to keep them that far. Charlotte does have a few great local lakes, if you're into boating at all. I had a 20' bowrider when I lived there, and trailiering the boat was super viable. Be on the water in <30min.
Humid? It gets hot (90+) for a few weeks in the summer, but its never unbearably humid. The up-side is no "real" snow, and super mild winters. I rode my motorcycle to work at least once a week when I was there.
Cheap Taxes? I can't stress how cheap it is (in the city of Charlotte, at least). My Property/local/school taxes all-in are UNDER $1300/yr (on a 1500sqf 3bd 2ba with a 1car garage built in 2007). If you live a little more rural, the taxes drop off too. I'm looking at homes New England now... and $6k+ in taxes annually is making me choke.
I should add, as a "car guy" that NC is south of the rust-belt. I was buying and selling VWs there for fun, and its amazing the difference between a 10-15 year old car from the north VS one from the south... jussayin. My next "toy" will absolutely come from NC or SC.
Good luck with your search!!