August is when most clients can get away, and when the usual destinations are at their hottest. The cooler alternatives are closer than most agencies assume.
August is peak booking season because it's when working parents and golf societies can get away together. It's also when the Costa del Sol and the Algarve are at their hottest, greens get stressed by midday heat, and a round that should take four hours turns into an early scramble before the course shuts down for the afternoon. Send a client there in August with no warning, and the trip they remember is the one where they played nine holes and spent the rest of the week by the pool.
Southern Spain and the Algarve are built for spring and autumn golf. August pushes tee sheets earlier every week, and plenty of clubs close through the hottest hours altogether. It's still sellable, it just needs managing. Book the earliest tee time the club will give you, and tell the client up front that the afternoon belongs to the pool.
Galicia, Asturias and the Basque coast sit on the Atlantic, so August there plays more like a mild June than a Spanish summer. The north is less well known for golf than the south, but a cooler round is an easier sell than a scorching one, and the flight times from most of Northern Europe are barely longer.

The Algarve gets the heat everyone associates with a Portuguese summer, but the coast further north doesn't. The same Atlantic air that cools Galicia keeps courses around Porto playable through the afternoon, instead of shutting them down for the worst of the day.

For a client who wants somewhere cool, August is when Scotland and Ireland are at their best. Daylight lasts past nine at night, and a jumper becomes optional. It's their high season: the courses run firm and fast, which is how links golf is supposed to play.

Wherever the client lands, the trip goes together in RoundPlan the same way. You build it day by day and price it as one package, whether the courses sit in Cantabria or in Fife.
Start the August trip in RoundPlan and build it day by day, wherever the group ends up going. The courses, the hotel and the price all live in the same screen.