We did two scouting trips to Spain before deciding, and I'd say they were the best money we spent on the whole move. The first trip was in May, and we fell in love with a town on the coast. The second was in January, on purpose, and we discovered that the same town was almost empty in winter, with most restaurants closed and the promenade deserted. That second trip changed our decision completely. We chose a town twenty minutes inland that has life all year round, and I'm certain we'd have been lonely in the first one.
So my advice: if you do one scouting trip, go in the worst month, not the best. You'll see the real place, and if you still love it then, you'll love it always.