Split must have changed a bit in the last 17-18 years. I did Croatia and Slovenia, and the advice I got was when you get to Split, split.
Of course, that was because I had the ability to go to and stay on the islands (Brac, Hvar, Korcula). That was more of what I was looking for.
One thing to keep in mind for the Mediterranean area is that most of Europe gets a whole month off for "holiday", and they flood that area in July-August. I went in early September, and the weather was still nice but it was not crowded at all.