I've made the trip up to Buffalo from Central Florida many times on business. Taking the I-90 to I-79 south, exit 57 in WV, take US 19 south to Beckley and I-77 S. You'll find that Charlotte, NC is just a tad over half way @ 659/mi. I'd get through Charlotte into S.C. to select an overnight spot.
Just south of the NC/SC state line at Exit 88 in SC, there's the Charlotte/Ft. Mill KOA if you need FHUs and during the summer, you'll need air conditioning. Easy on and off the Interstate. A little further south at the Dave Lyle Blvd exit, there's a Walmart I've dry-camped at, about a mile east of the Interstate. Continuing south on I-77, you'll find a FlyingJ at Exit 73 that's good for an overnight. A great alternative to the KOA is
Ebenezer Park administered by York County. Ebenezer is close to 5 miles off the big road in the northern part of Rock Hill. First come, first served, it's popular with the locals and your arrival should be planned for Sun-Thur. Mentioned due to camping prices in the area.
Fuel prices will be cheaper at the Indian Reservation in Silver Creek, NY., Wytheville, Va., and S.C. Enjoy your trip.
P.S. From Buffalo, there ain't no way I'd come down to Florida on I-95 thru the N.E. I made the trip north on I-95 from NC to Buffalo... once... LOL.