In Valdosta, the Country Inn & Suites is very, very nice - I'd choose it over any other place in town (or southern Georgia/Northern Florida, for that matter). If you want something less expensive, the best Econolodge I've ever seen is in Valdosta at the same exit (clean, modern, interior corridors, etc. - built just a few years ago).
In Lake City, try the Holiday Inn. A bit expensive, but nice, with amenities not found at most roadside hotels.