Down here in the sweat belt, I used to run the AC full time due to condensation & humidity concerns. After paying some big $ power bills, decided something else was in order. Through trial and error, settled on a carpet dryer fan. These produce a "collated" (for want of a better word) and fairly high velocity air stream.
The boat has a very open floor plan - may not be applicable in more confined interior settings. With the fan in the V-berth, directed aft, and air stream directed about 15 degrees above horizontal, it gives sensible air movement all the way to the aft stateroom. That is sufficient air flow to prevent condensation/mold. Worked well for two seasons. The fan is on 24/7 regardless of the season or temp. I got mine at Sam's for $60-70.