We have spent the last two spring / summer vacations (May & June) bareboat
chartering out of Marina Kastela near Split. It is paradise. Friendly people, easy to get to, not too expensive, moorings when you need them, and plenty of sheltered coves to drop the hook.
On the down side:
are not cheap
The Bora (mentioned previously) is pretty vicious. We recorded 40 knots on our first night in Marina Kastela. Thankfully having arrived late we had not tried to set sail that night.
Visit the busiest anchorages/towns (Hvar) on a Saturday when all the charter
boats are changing over
May, June is not too warm
Vis is our favourite place the town is beautiful and relatively unspoiled
Any number of coves to anchor
in throughout the islands.
Dolphin and tuna in abundance
Conclusion: The Croatia
coast is a paradise, can't wait to get back.